If you know how to actually do research and understand market psychology, it's definitely not impossible to hit big with only a starting balance of $20. The cryptocurrency markets is a very very inefficient market. Lots of projects are heavily overpriced, and some are heavily underpriced. You just need to look for the latter and allocate money smartly.
Personally, I've made GREAT picks throughout the years by doing mid term investing, especially this year. I could've still multiplied my money if it's the case that I started with a very low 2-3 digit amount, but having extra money inflow from the sigcamp and a small online business definitely boosted my investment capital. And no, I'm no son of a millionaire and I had no money to start with.
You don't need to be filthy rich to be part of crypto trading. As you said you can start with 20$ and still earn huge profits. The key to success here is that you need to do research and gather knowledge before jumping in with huge capital. Most of us don't wanna do this laborious work rather want to get rich via shortcuts. There is no shortcut to success whether its crypto trading or any other trading. You have to work hard, if you get this you are on right track.