I'm guessing he walks. He's a highschool pitcher. He can pitch in college for a year and get drafted higher
in which case he's a moron, giving up $3 million and a three year jump on his pro career in exchange for hoping that he can improve his stock and maybe get another $3 million (and maybe go in the 11th and get 100k). I don't think it's about the money though, he doesn't seem to come from a family that is desperate for it (though it's impossible to know) and college is a great experience