Casino owners also earn a lot of money - just like people behind crypto exchanges as ell as miners are making a lot of money. But the "investors" are like the gamblers. A few are lucky, just like the guy who wins at the slotmachine, but the vast vast majority will come out of this as losers.
Then by all means make the argument that exchanges are a stupid-people tax. Or that gambling in general is a stupid-people tax. You could even argue that the vast majority of ICOs are a stupid-people tax. But that's not what your thread title says, so it looks like you're making the wrong argument.
Exchanges != Bitcoin.
Two parties can transact peer to peer without introducing any third party middlemen to take a cut. That's how Bitcoin was designed to be used. If your primary motive in using bitcoin is to speculate (gamble) for an increased quantity of fiat, then sure, there are lots of risks and you could easily lose. But that's not the real purpose of Bitcoin. If you aren't using it in the way it was intended, who's really the stupid one?