bro, it's not just about the money. He's promoting himself, building up a portfolio, learning new skills and entertaining himself.
I have considered doing this before, contests etc. but I'm not sure I can breakdown the actual cost of doing it, the benefit, and risk to be able to see what one actually gets from the time devoted.
Not to say that I might not do other things that cannot be quantified easily either, but in the contests case I want more quantification, I guess it just seems more likely a waste of time to me.