I think it's ok to drop out of college to grow a startup. But it's a terrible idea to drop out of college to start a startup.
It's okay to take risks but no reason to overdo it.
But if I were an investor I would seriously question your decision making ability based on the fact that you dropped out of Princeton your senior year with about 8 months to go.
If you want to take a somewhat data driven approach, I'd also ask how many successful startups STARTED after dropping out. I can't think of any off the top of my head. (Hint: Microsoft and Facebook don't fit this criterion).
College is a nice passtime, but you shouldn't let it get in the way of your dreams. If you need to start a startup, do it. There is no correct path. You are just as likely to fail no matter what route you take, so take the one that feels like the best opportunity for you.