One of the most common answer tropes to the "start-your-life-over-at-x-age-with-all-your-current-memories"-question is people saying that they'd buy Bitcoin or invest in Stock XYZ that they know will be successful to easily become multi-millionaires.

Now, with publicly traded stocks, I don't see a big problem because they (generally) actually correlate to a real-world value. For example, if I buy a \$10,000 worth of cheap Apple stock in 2005 for \$1 (and didn't sell), I'd likely be a multi-millionaire today. Sure, my buying the stock probably marginally influenced the current price that trading day, but in the grand scheme of things, I find the "butterfly potential" rather low.

Bitcoin, on the other hand, is far more volatile. For example, in 2010, I could buy Bitcoins for single-digit cent amounts which would be worth individually over \$50,000 dollars today. So, if I spent \$1000 bucks buying them at ten cents a pop, I'd have something north of \$500,000,000 today. Unfortunately though, I'm worried that by disrupting the timeline and buying some Bitcoin, it never becomes valuable for some reason. For example, maybe some of those ten thousand Bitcoins I bought would've been used by influential people in the early Bitcoin community, and my buying-and-holding strategy would take those early coins out of circulation, thus putting a damper on someone's eventual Bitcoin evangelicalism. Now, a potential solution to this problem would be to mine them myself, and thus I'd only be increasing the overall mining difficulty slightly which might not influence the timeline as much.

So, the question:

In the earliest days of Bitcoin, how many Bitcoins (and when) can a time-traveler buy while avoiding disrupting the timeline too much and ensuring that the price still eventually spikes into >10k territory?

And, as a secondary bonus question:

An appreciable amount of Bitcoins in existence are "lost", so what would happen when my time traveler attempts to sell her (potentially) multi-billion-dollar wallet composed of coins that were thought lost? Also, would it even be possible to convert Bitcoins into USD at such a scale?

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – L.Dutch
    Commented Mar 11, 2021 at 4:40

10 Answers 10


Frame Challenge: It will butterfly in your favor, not against you.

By buying and holding bitcoins you are making the buyer's market for bitcoins more scarce. So instead of devaluing it, by refusing to sell them you are actually making them MORE valuable in the future. If anything, this will cause the value of bitcoin to grow even faster making it an even attract for influential early investors, not less.

The important thing here in terms of influential early adopters is to make sure that you never clear the entire market on any given day; so, instead of going back to a certain time and acquiring all of the coins available for sale that day, you should go back an acquire some of the coins every day over a period of time until your budget is spent.

If you reduce the stock of new available coins by 50% each day, and a fixed number of should be buyers show up each day with a certain amount of cash-in-hand to buy up the whole stock, then those selling will increase their prices to meet the demand. In this way, those early adopters still went and bought \$100 dollars worth of bitcoin, but instead of buying 1250 coins, they bought 625 coins worth the exact same total amount of \$100.

The other way you prevent yourself from crashing the market is to make sure you do not pose the threat of becoming a majority owner (by buying up 50% of the total bitcoins) Now, keep in mind that you do not actually need to be sure to own less than 50% of bitcoins, you just need to make it look like you don't. By splitting up your holdings into multiple wallets, you can hide the fact that there is a person amassing and holding coins, then once the market grows enough for your stockpile size to no longer matter, you can consolidate your coins into a single account. Having a single wallet by 2020 will make confirming your identity during your off-ramp much easier for complying with anti-embezzlement laws.

The value of bitcoin will not take a dive until you decide to sell all of your coins thus flooding the market. The good news is that even if you devalue the market by selling out, the available stock in 2020 is MUCH larger than it was in 2010; so, selling out would have a relatively small impact on the coins available in market compared to when you bought them; so, your big sellout itself would not cause the market to crash or overextend buyer's interest, but it could trigger the bubble to bust if everyone else starts panic selling as a result of your actions... but at that point, you've already made your fortune.

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – L.Dutch
    Commented Mar 10, 2021 at 19:44
  • $\begingroup$ With a "24-hour trading volume of $57,414,351,300 USD" with a bit of discretion, you could move millions a day without anyone noticing let alone panic. If you have enough, you could re-invest that to artificially increase the price. Investing 10% of your spoils to inflate the remaining 90%... $\endgroup$ Commented Mar 10, 2021 at 23:05
  • $\begingroup$ I thought a major selling point of bitcoin is to obscure your identity. Does he really need to "hide the fact that there is a person amassing and holding coins"? $\endgroup$ Commented Mar 11, 2021 at 1:03
  • $\begingroup$ @ShawnV.Wilson There's an inherent risk in the way Bitcoin (and a lot of other cryptocurrency) works with its distributed ledger system. I'm no expert, but as I understand it, all transactions are essentially 'confirmed' as valid by everyone else in the 'system' as a majority vote. If you hold >50% of all Bitcoins, you can refuse to validate any transactions anyone else makes, which would be catastrophic for the market. People would be aware of this risk as they'd see all those coins in the one wallet. See investopedia.com/terms/1/51-attack.asp for some more reading. $\endgroup$
    – Kayndarr
    Commented Mar 11, 2021 at 3:33
  • 2
    $\begingroup$ @Kayndarr The "51%" refers to computing power, not how much Bitcoin you hold in total (which does not affect Bitcoin's security). As detailed in the original whitepaper, a proof-of-work scheme is used because it provides a simple way of having a distributed vote that cannot be easily tampered with (as opposed to, say, one vote per IP). That's what Bitcoin ultimately is, a secure consensus building system built for a very specific purpose. $\endgroup$
    – adrian
    Commented Mar 11, 2021 at 3:48

Be the Butterfly

Nobody knows who Satoshi Nakamoto is. Who's to say it wasn't you right from the start? Go back in time and be Satoshi Nakamoto. Create Bitcoin using what you already know and mine the early coins. Satoshi Nakamoto is worth almost $35B.

This way you haven't changed history at all and still gotten super rich.

  • 3
    $\begingroup$ This seems like it would change the timeline a lot more. If you decide to launch it right before they do, they may accuse you of stealing their idea (especially if they've been planning it for a while), and that could affect public perception of the currency. If you launch it much earlier, it may simply not be the right time. What would otherwise have been early adopters may look at how long it's been around and decide it's probably not going anywhere. $\endgroup$
    – NotThatGuy
    Commented Mar 10, 2021 at 12:12
  • 2
    $\begingroup$ There's also the issue that Satoshi holds all of his/her/their BTC, which is a significant support to the market. $\endgroup$ Commented Mar 10, 2021 at 17:40
  • 1
    $\begingroup$ This assumes a significant amount of technical knowledge to be able to create Bitcoin. The underlying technology was significant and interesting when first released and has been refined since then. It also assumes a lot of luck. If the right other people hadn't also gotten interested in bitcoin fairly early it would not have taken off. $\endgroup$ Commented Mar 10, 2021 at 18:03
  • 1
    $\begingroup$ @NotThatGuy In this scenario, "Satashi Nakamoto" doesn't actually exist except as the nom de guerre of a time-travelling Dragongeek. $\endgroup$ Commented Mar 10, 2021 at 21:58
  • 1
    $\begingroup$ Ok, I might have misunderstood this answer. I might suggest editing it a bit to avoid future confusion, e.g. "Nobody in the present knows the true identity of the creator of Bitcoin, who goes by the presumed pseudonym of Satoshi Nakamoto". I wasn't aware of this fact, so I assumed you're talking about a different timeline where this is the case. You could also mention that it's like an inverse grandfather paradox (or something like that). That they actually need to go back in time, to prevent a paradox. $\endgroup$
    – NotThatGuy
    Commented Mar 10, 2021 at 22:14

Don't buy - use advances in GPGPU tech to become the first person to use the GPU to mine bitcoin

Every 210,000 blocks, the block reward for solving the hashing problem of the accumulated transaction history halves. It started at 50BTC.. This problem is computationally expensive. Initially it was done on the CPU. Eventually it only became economical to do on the GPU. Now it's only economical to do on specialised hardware. If you beat that jump from CPU to GPU, you can make bank.

Before you leave, download a copy of an openCL GPU miner, print it out if you have to (it's tricky to memorise - it's nasty nasty code) travel back to August 28th 2009, and immediately go (ie wait in line in front of the apple store for opening if you have to) to purchase the new Snow Leopard OS X PC with OpenCL 1.0 support, released that day, and install the prototype bitcoin client (release January 2009 - so 7 months old).

Bitcoin has been growing for 7 months - every early action that is going to be of importance has already happened, there's thousands of people mining already, just they're not being very efficient about it.

While everyone else is using the CPU to mine at 100,000 hashes per second, you can jump onto the GPU and blitz through those first easy blocks on hardware of the day at ~20 million hashes per second. GPU mining started being possible for everyone else mid 2011, and when they start GPU mining, you have 10 years of performance optimisations made to the algorithms on top of them.

enter image description here

This graph represents the entire network hashing capacity through history, the bottom line there that should be labelled "0.0001" (yeah good axis label trimming right) is 100 million hashes per second. The network as a whole is mining ~250 million hashes per second, your mining 20. You are accumulating 10% of the worlds bitcoin on your single computer.

If you stop on Christmas day 2011, you're looking about ~700,000 bitcoins in your possession of the 8 million already in circulation at this point in time. You've moved the graph only slightly upwards, and 4 million have been lost, so you're skimming off the top is barely worth a mention.

Or even better, bring back the specialised hashing hardware. It's USB compliant, looks like a flash drive, and you can get drivers and control software for Windows XP so it should run on these computers. That might be too greedy however, if anything risks scaring off those early investors it'll be someone getting multiple gigahashes-per-second that early.

  • 7
    $\begingroup$ Butterfly effect also here: somebody would notice that somewhere there is someone eating the largest slice of the pie and investigate, zeroing the advantage. Or not? $\endgroup$
    – L.Dutch
    Commented Mar 9, 2021 at 14:26
  • 4
    $\begingroup$ @starfishPrime. There are no known future blocks. A single bitcoin transaction will alter the hashing solution of every subsequent block for all history. The hash follows a strong-waterfall condition which basically guarantees the odds of each subsequent bit being flipped being exactly 50%, totally changing the future as much as possible. However probability still applies, and it will be directing the randomness of strong waterfall hashing towards likely, typically repeatable, outcomes. $\endgroup$
    – Ash
    Commented Mar 9, 2021 at 15:07
  • 8
    $\begingroup$ By doing this, you'd be capable of performing what Bitcoin calls a "50% attack": you'd have more than half the world's hash power, and would be capable of re-writing the blockchain. This is the one thing that's pretty much guaranteed to destroy Bitcoin. $\endgroup$
    – Mark
    Commented Mar 9, 2021 at 20:53
  • 4
    $\begingroup$ @Mark Only if people know you've got it. Bouncing your traffic around the net would make it look like several 5%s each using well-known proxies for some reason – suspicious, but nothing on a 51% attack. $\endgroup$
    – wizzwizz4
    Commented Mar 9, 2021 at 21:25
  • 2
    $\begingroup$ @JesseM a future blockchain is useless random noise in the past. that may work with the first block you get to, but any change in time stamps or ordering of any transaction (say because a server was processing your request and delayed anothers by 1ms), and all future bits after that point have a 50% chance of being flipped. See strong waterfall condition discussion above. The good news is perfect randomness works with statistics and probably. So despite all the bits being equally likely to be flipped, the coins will tend to go to the same places long term. $\endgroup$
    – Ash
    Commented Mar 10, 2021 at 20:49

Nearly a million coins were "supposedly" mined by Satoshi and don't currently directly effect bitcoin market price, nor have they ever. Simply time travel back and mine coins under the "guise" of Satoshi by replicating the way that those coins were mined. As such, the coins would be considered Satoshi's and no one is the wiser other then a slightly different difficulty graph early on which would simple be attributed to Satoshi having turned on another CPU to mine with. There is currently evidence of the fact that Satoshi did possibly turn on other CPUs to also mine with, there are peculiar patterns to the mining to suggest such. This could be Satoshi, or evidence of time travelers doing what I explained. There is no way to tell until the owner of the coins reveals themselves.


It depends on how much research time you have here in the future before you depart on your journey into the past.

Thousands, if not hundreds of thousands of coins have been purchased and lost over the years by hard drive crashes, forgotten wallet passwords and other calamities of fate. If you could find the current day incarnations of those individuals who suffered those permanent coin losses and interview them about the details of their loss, you could then go back and arrange to meet with them just before each of their catastrophes to buy the coins from them, giving them a too good to refuse profit with the single condition that they forevermore tell people that the coins were lost in a calamity of fate.

  • $\begingroup$ Or just camp outside this guy's house and check his garbage each morning: cnbc.com/2021/01/15/… I mean, it's a bit of profiting off of someone else's loss, but you aren't making him throw the drive out, he does that all by himself. Maybe you can anonymously send him some money later on. $\endgroup$ Commented Mar 10, 2021 at 0:50
  • $\begingroup$ Poaching his trash would only get you access to the computer that the wallet is on but not the password to the wallet. $\endgroup$ Commented Mar 10, 2021 at 2:17
  • 1
    $\begingroup$ Time travel far enough into a future timeline to when Quantum Computing is actually a meaningful thing! $\endgroup$
    – JVC
    Commented Mar 10, 2021 at 2:33
  • 1
    $\begingroup$ Most encryption methods and "best practices" that old are not cryptographically secure by today's standards. In 2010ish, it was really easy to steal passwords from pretty much any system you had direct access to. In most cases, these people were probably using passwords you could hack with a 5 minute rainbow table attack anyway. $\endgroup$
    – Nosajimiki
    Commented Mar 10, 2021 at 3:13

I think you could treat this problem stochastically.

How many X can I take out of a dynamic system before Y happens? Where X could be molecules of water on Mars before Y the seas dry up, or X could be atoms of O2 before Y I can no longer breathe.

You could model this as a liquid, where the amount of movement of X in the system is fairly low. In that case, the reaction rate depends on the total size of the system and the concentration of the reactants. Applied to currency, the total digital currency economy is only 830 million dollars in 2020, according to Yahoo Finance, and say one digital currency is 50% of that your heat of reaction is added value on your currency, it’s not necessarily linear, but taking 5%, 10%, 50% of your currency out of the system to sit on the sidelines reduces your “heat” creation by about as much. Rate = k A, where k is some constant and A is the concentration of the digital currency remaining to “react” in the marketplace.

So let’s compound this continuously to look at the damages over time:

The compound interest equation is I = Pe^(rt) , where I is total value at time N, P is how much principle you start with (which isn’t changing so you can ignore it), r is interest rate and t is time (in years). So, let’s say you take 25% out of the economy 25 years ago. I = 1 e^((1 - 0.25) x 25) = 139 million, if I did the math right. That’s after your time traveler has done his work. What was lost? e^(1 x 25) = 72 billion.

That’s likely exaggerated since the base interest rate is hardly 100%. Feel free to play with the numbers. But, it doesn’t take much to do a lot of damage.


Historically, you want after the guy who bought in at ~$10 and evangelized to all of his rich friends - which started the run up. Prior to that, it was geeks who were buying pizzas with bitcoins - and going nowhere.

You want that guy to get his at a good price (so he's invested in evangelizing); and buy/mine after he starts talking it up to various other rich people (which will help him sell it on FOMO grounds), so they bring money to the game.

Can't recall his name right now, but read some history of bitcoin.

Of course, if you go back in time, tell Satoshi to modify it so it's not a clusterfuck - and you won't have all the splintering and BS that's going on now. Of course, maybe it's for the best. Candide, anyone?


Don't buy - just take some that would otherwise be lost.

  1. Find someone who mined coins in 2009-2011 but lost them in the original timeline.
  2. Go back in time, stealthily hack them and copy their wallet.dat . You can take advantage of any exploits discovered since then.
  3. Wait and Profit!

For an extreme example, there was an exchange bitomat.pl that irretrievably lost many coins because they used temporary server instance that was shut down and no backups. However these coins addresses are known and it might raise suspicions. To avoid timeline disruption, it's best to take coins that everyone, including original owner, forgot/wiped the address. There are plenty of cases, as bitcoin was deemed worthless for years.


You are thinking too small.

If you can go back once, then you should be able to go back multiple times.

  1. buy gold when the us was still on the gold standard (pre 1972 I believe). Use this to setup a long term relationship with a bank for storage (i.e. multiple safe deposit boxes).
  2. buy sun microsystems when it is a penny stock.
  3. buy apple when it is a penny stock.
  4. buy 100,000 or more bit coin.
  5. buy star wars toys and keep them in mint condition
  6. buy rookie baseball cards.
  7. assuming you can get back far enough, buy early edition dc comics
  8. buy x-men 97
  9. buy as many boxes of early pokemon as you can.
  10. buy as many black lotus cards as you can.
  11. buy editions 1 - 3 (or more) of the TMNT comic.

Each of those should have little, direct, impact on the other and can be stored in a bank vault for a long duration.


First of all, time travel is not real.

Now that we have gotten that out of the way, we can all agree that time travel is science fantasy. This means, for story telling, that as long as the system of time travel that we are employing is internally consistent, anything goes. The joys of reading time travel stories are to watch the author concoct and deploy wonderous structures that work (that is, are consistent) and see how the characters flounder their way through the plot.

So you get a large cauldron, throw in questions of free will, block universes, butterfly effects, and grandfather paradoxes, then stir vigorously. What could possibly go wrong? We hope all sorts of things go splat otherwise why bother to read the story.

One key question that the author must answer is, can a time traveler change things in the past that eventually change the future and to what extent. The block universe says that everything that could happen has already happened (at least in some sense); The timeline is already baked and all you time travelers can just pound sand. The multiverse says that every outcome of every event creates a new universe; each change that the time traveler makes sends the traveler into a brand new universe (cue the sound of sand being pounded). The fluid timeline transforms the time traveler's nudge into widely sweeping changes up (or is it down?) the timeline; metaphors for the fragility of life and mind-twisting paradoxes abound. Every author makes up their own system; there is no central authority that governs the genre.

So the question is, how do you want this world that you are building to work? Once you make that decision, the question becomes, can you convince the reader that there is some sanity in the system?

A final comment about butterfly effects with respect to time travel within a fluid timeline. The time traveler makes a change in the past and the timeline re-arranges itself so that empires fall and women's fashions change. The engineer in me wonders where all of the energy to make that happen comes (came?) from. The events of the timeline, already in place, suddenly are uprooted and transformed into something different. I read a lot of time travel fiction and I have never seen an explanation that makes any sense of that effect. There are stories in which the timeline "resists" all efforts to create changes. I am thinking that these stories have the right of it. Just a thought for the conversation.

  • 4
    $\begingroup$ I'm using the "infinite worlds" approach to time travel as this removes all paradoxes and is easy for even non technical people to "get". In it, my protagonist never actually travels backwards in time, they're simply jumping into an alternate universe where everything is the same except it's 10 (or however long) years earlier. So, when she arrives in the "past" it's not technically her past, it's just a past identical to the one she experienced. $\endgroup$
    – Dragongeek
    Commented Mar 9, 2021 at 15:28
  • $\begingroup$ even if it holds some truth, but there are a lot of low-quality fantasies out there and it is nice to see someone who wishes to improve things. Not everyone may be happy by half vodka half juice and shake 3 times. There are enough people who would like to see things spon in some more realistic way. $\endgroup$
    – MolbOrg
    Commented Mar 9, 2021 at 15:39
  • $\begingroup$ This answer is outside the scope of the question asked and would have been better posted as a series of comments. $\endgroup$ Commented Mar 9, 2021 at 16:54
  • $\begingroup$ You can write this on pretty much any question about time travel (of which there are many). It doesn't in any way address the specifics of or answer the question, which means it's probably not all that appropriate as an answer. Although asking which model of time travel is used might make for an appropriate comment on the question. $\endgroup$
    – NotThatGuy
    Commented Mar 10, 2021 at 13:09

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .