Hehe... well if we're going to define college only as writing papers, hooking up and getting shitfaced, then I take back what I said.
I guess I assumed it could also be used to experience new things, learn from a variety of courses, meet people, get some real world experience via internships, etc. - with the added benefit that it isn't necessary to have fully determined purpose and that the experience should go along way in helping you find yours if you try. You may never get it back, but it's certainly not wasted if it helps you ultimately choose what to do with your present/future life.
I went to college not really sure what I wanted to do, discovered something as a result, am currently doing it and am moving in a slightly different direction right now. If years from now this new direction actually leads me to a place where college would have been not required - I wouldn't regret having gone one bit, because it was still a critical experience in my life that helped ultimately define my current/future purpose.