Why non-geographic nations (micro or otherwise) cannot work;
Back in my days on EVE online, I actually answered this question on their forum when someone suggested that EVE declare itself a nation. That idea (and by extension this one) cannot EVER work, for one very simple reason.
Humans consume stuff.
Sure, the idea of having to pay no tax sounds great, but nations have taxation regimes (not primarily for wealth redistribution as many think) but for the infrastructure and services that's not economically viable for others to provide.
Roads. Police. Hospitals (at least here in AUS, sorry USA). Schools. The list goes on.
You can't just claim in (say) Australia to belong to be a citizen of another country and continue to live here without paying taxes, for instance. Non-Australian citizens who work here still have to pay taxes (after all, they're using the roads, hospitals, etc.) and even Australians abroad pay the difference in tax between their resident country and what they'd pay in Australia. This covers their right to come back at any time and use the infrastructure already in place.
Another important reason to belong to a geographical country is mutual defence. A part of the national budget goes into building a military force whose function is to protect the citizens of the country from attack by foreign actors.
The thing is, if you give up your local citizenship for a micronation, you lose access to all the benefits that your citizenship affords, including residency. That's a problem, because a micronation that doesn't charge tax doesn't give you a viable alternative to those benefits.
So; perhaps you're joining to allow you to claim that local laws regarding online activities and the like don't apply. After all, you're a citizen of another country, so online or import restrictions don't apply to you, right?
Australia (like many other countries) doesn't differentiate between citizens and non-citizens when considering import or online violations. Technically, these are the same thing as when you look at a site, the data for that site caches on your desktop or phone, meaning that you've 'imported' that data. But, I digress.
You can't get around importing restricted items (digital or otherwise) by saying that you're not a citizen. Some laws, like import regulations, apply to anyone who interacts with your nation. This means that the act of commissioning a restricted import is already an offence, regardless of your domestic status.
The only reason I can think of to become a citizen of a micro nation is so they can hold stuff on your behalf. This is almost the exact business model of Sealand, which affords a digital 'safe haven' for websites and other data holdings that are considered illegal in mainstream jurisdictions, like gambling websites targeting countries where this is illegal.
So; if you want to get a lot of citizens quickly, offer them free web site hosting, and emphasise your lack of legal oversight on servers within your sovereignty.