Both Google and Yahoo! were started by two Ph. D. students who decided they had more important things to complete than their dissertations. I find that funny as I try against all odds to change the very structure of modern academia rather than working on my dissertation 🙂
(Of course, my dissertation’s basically done already. Writing it was never the problem.)
Seriously, though, I think that there’s something about writing a dissertation that makes you realize there are more important things in life.