As many have said, the bulk of the value of going to college is in the signaling they're able to provide. You're paying (overpaying in my opinion) for the infrastructure they've put in place to adequately assess your abilities in a way that employers can trust.

Say you pay someone to do an inspection of your home that the gov is requiring before you can sell. Has that inspector taught you anything or made any tangible improvements to your home? No. What they've done is signal to the gov and buyers that your home passes inspections.