For every 1 Zuckerberg there's at least 1000 other people who dropped out to start a company who crashed and burned. Also, just learning to finish big things that you start is a very handy skill to learn and practice, school is no exception.
Correct. On the flipside, just because you finish college, doesn't mean your startup will magically succeed either. It's more the fact that you can finish something that you can make have value for yourself. Too often we think we need to rush out and leave college for good, as if at 19, the opportunity to do a startup will disappear in 3 years.