Me, I got a SysAdmin job rather than going to school, and continued on in that direction. Sure, when I was my sister's age, I made 5x what she does now, but I don't think that was her primary reason for going to school.
I mean people spend that much on cars that aren't any more utilitarian than a $15,000 civic, so why not spend it learning an interesting skill while living around interesting people?
It's harsh but there are only 2 types of people in college. Those studying towards the field they want to work in, and those pursuing a hobby full-time. The latter would be better served spending the money on first-hand experiences instead of reading about it other people's second-hand.
I think the most important thing you miss out on is the ease of finding peers to discuss the subject with. My degree was in math and physics, and, while I didn't talk to many people about physics (which I feel I don't know very well, btw), I had a good friend in math, and we would often hang out and discuss it. We took a lot of the same classes together (even outside of math), because we got so much out of our discussions.
So the decision to go to college is governed by the logic of college as investment, but then the content part is guided by the emotion of college as personal self-realization.
So we end up with a society where countless people pour thousands of dollars into attending college for fundamentally emotional reasons. Or even worse, for mistaken factual reasons about the practical benefit of their education.
In other words, as Ted Rall put it even before college costs doubled, college is for suckers:
http://www.metroactive.com/papers/cruz/09.26.96/student-9639...
---
Although America's universities are churning out a steady stream of brain-dead simpletons, our society relies almost exclusively on college credentials as the central determining factor of social status and employment opportunities.
---
I know it is a farce. But I also want the HR departments across the country to know that too. (I guess the lesson is: don't work for companies that consider college degree + GPA as the main determinant for your employment criteria).
We all grew up brainwashed with the idea that "4 year college"="better jobs"="better life". Colleges have been raking in good profits all these years by exploiting that mantra. It is really hard to all of the sudden deny it and go against the popular opinion.