To learn. To advance your understanding of a subject. To improve your skills. The list goes on.
Some people consider learning and knowledge ends in themselves. Others consider them only means to an end.
Earning a degree from a tech school, community college, or university isn't the only way to learn, but it is arguably the best way to learn many subjects, at least if you think the best way to learn is from an expert.
I think a lot of the frustration and bitterness in this thread stems from resentment of the traditional four year university degree - many people see it as being 'forced to learn about shit you don't care about to get a job that has nothing to do with this or that class.'
What these people don't understand is that a long time ago, the only people who attended university were the very wealthy and the very bright. The very wealthy acquired an education because they had the idle time to do it and didn't need to work, and the very bright went to university because they liked learning (and the very wealthy paid for them to go in the form of scholarships).
Middle class folks who were reasonably intelligent didn't go to university because they could earn a middle class living without needing a four year degree, and they either couldn't afford to go, or just weren't that interested in going. A lot of these people went to trade schools instead, back when Americans did things like welding, before most of those jobs got offshored.
It's essentially no longer possible to have a middle class job without any sort of degree unless you're willing to perform a dangerous, or dirty, or otherwise shitty job that's only appealing because of its pay. Many middle class jobs that required only a high school education or technical degree simply no longer exist. And now because of social engineering, everyone can 'afford' to go to university via loans. 18 year olds are told to go to university otherwise they'll never get a good job if they don't. They enter university without the maturity to realize they're making an enormous investment of time and money, and they're told to pursue their dreams regardless of economic realities - if they even have any dreams at all.
I'm as invested in the university system as anyone can be, but to be honest, our current higher ed model is unsustainable. There are too many people in my classes who are not intelligent enough and/or not interested enough, who should instead be in trade schools - but again, where are those jobs? The only growth industry where a technical degree is sufficient seems to be IT, because as computer hardware and software evolve, it's becoming very apparent that many IT jobs can be performed with a technical degree rather than four year university degree. I fear that IT's insufficient, though. Technology is absolutely one of the factors widening the gulf between the haves and have nots in the US, along with offshoring.