The problem I have with free college is that college, while expensive now, is already nearly compulsory for a lot of jobs that don't require it. A degree in any irrelevant thing is used as an arbitrary deciding factor. Free college will make for compulsory college as everyone will need a degree to have a chance. Then we actually lose value from the opportunity cost of people not working.

Disclaimers: obviously, yes, I think education is great in general. And I actually don't mind social education. I just think it's easier to get this wrong than right.