In my opinion, people dropping out of school for YC shouldn't be doing it because they see an alternative opportunity - they should be doing it for a variety of other reasons. The mental calculation should not be "I could do a start up and make money now, or I could do 3 more years of school and make 140k/year comfortably." It should be along the lines of, "I know I'll succeed, and I can't wait to do it."