The scenario: You are from the distant future, and are trapped in a parallel universe in the mid-1980's. You cannot expose your true identity and your only resource is a hidden laboratory where you can fabricate some high-tech gadgets. You don't want to share your technology because it would mess with civilization. You need resources to build a portal in space that will get you back home. How do you learn about this society, create an identity, and make as much money as possible as fast as possible?
Your big advantage in coming from the future is knowledge. You know which companies are going to rise, so you can invest in them. You might remember results of games/races/etc., so you can bet on those.
Betting (similar to Back to the Future II) is actually weak - if you win too many times, someone would suspect fraud. But if you use it once to gain a starting capital, and then invest that in what you know is going to be on the rise, you're set for financial success.
For comparison, imagine being able to go back a mere ten years into the past, and telling your past self to invest in bitcoin.