The idea isn't to stop people from doing something stupid but to stop people from trying to get people who aren't in a position to weather risk to do something risky to increase their own likelihood of profiting.
Forex has regulations for unsophisticated investors in the US.
Gambling is different in that the user goes into it knowing that they have a negative EV. Lots of people lose everything gambling no doubt but while they may hope to win they know the likelihood is that they will lose.