It's pretty obvious what Paul Grahams goal is. He wants to pay some kids a laughable amount of money to write code for an idea he likes. He then uses his popularity to promote those websites. He basically gets coders for cheap. He's not stupid or anything, it's just he gets the better end of the deal than the kids he gives $5k to.

If you have an idea that paul graham likes, you're better off not taking the money.