I know it isn't an investment, but in the last few years some "high risk" investment funds have appeared, and in them you can either lose it all or earn a lot of money.
Isn't this basically the same as gambling? Wouldn't it be faster to just deposit the amount in a casino? At least you'd be able to spend your earnings much sooner

To knowing some way (especially gambling) is a kind of high risk investment or not is try to read them. How long you can loose or take profit in that way. And then, how much you can get or lost in some regular time.
Make a rule for your self. Even if it's for gambling, you have to make the point, when is the ROI.