It's actually very similar to the stock market, it's just that there's no company backing it and there's no rules. It's why people were warned against investing so much not that long ago.

In Europe meanwhile, investing in the stock market is getting harder and harder, as new european rules (e.g. MIFID II) make any stock broker require to fill in a test and whatnot to prove basic stock market knowledge and competency, plus accept the risk to lose money explicitly.

There's a lot of people that invested money in the stock market they couldn't lose, due to promises of huge returns. Sounds familiar, doesn't it?