Don't knock it 'till you try it.

If you're a moderate or greater sports enthusiast, with ~20 bucks to spare, you can make turn it into a few hundred pretty quickly, like within a week or two.

I legitimately use it to supplement my income, started with 20 bucks.

I actually think that's an awesome business. A) eSports are growing, but many have not found clear revenue models. B) Would be awesome if you could figure out a way to actually fund leagues based on revenue brought in. Almost a horse-racing model. It's difficult because of gambling laws, but a) might be fine in some states or countries and b) the betting is not related to the actual score of the game so gambling abuse is less likely (although still not impossible, much like point shaving). It's also still really hard to help someone's outcome on their bet a ton since it's mostly bet in large pools. Would be like trying to help rig an NCAA bracket pool vs trying to fail to cover in a NCAA game.