Why do people who shouldn't be in college go to college?

Or to universities at least. A sizable fraction of students at most regional and even state universities, I'm going to guess about a third, should be in trade, technical, or community colleges getting very specific training. (There is probably another fifth or so that be better of financially from attaining technical training.) This group has neither the desire nor the ability to attain an education with a sizable liberal arts component or to contemplate the great questions of life such as Why am I here?, What constitutes the good society?, and Is Britney Spears ever going to make it through rehab?

The only conclusion I can reach is that this group of students only goes to college to increase their future earning power, and there may be some social considerations as well such as attaining status or finding a mate. However if this was the case, then they would take actions that would actually increase their earning power like reading and studying.

If employers use a university degree as an indicator of ability, are they looking for the effects of the degree or what caused the degree to be obtained in the first place such a minimum of intelligence, work ethic, and dedication? If a degree acts as an indicator of ability, it would be much cheaper from a social perspective for employers to just hire kids straight from high school at very low wages with short time commitments to determine if they have the necessary attributes instead of society wasting 5 years paying for huge chunk of their college degree.

Or maybe this group of people just goes to college for 4 to 6 years to prolong adolescence.