Just look at lotteries.
I don't believe in them because when you consider operational costs, less money comes out of the lottery than goes in, so if everyone simply didn't bet on the lottery, they would have more money than if they bet on it.
But everyone who bets thinks "but what if I win?"
at least the lotteries and las vegas publish their odds. Losing to the terrible math is probably better than playing against someone with inside information.