I spent my 20s getting a PhD. I don't think I've ever gotten the most out of my degree professionally, but as a way to spend one ones 20s, it wasn't too bad. I never had more than about $10K to my name until sometime in my 30s. Having a career in tech certainly helped--I took very few loans, but the ones I did have were paid off within five years of exiting academia and smartening up about my career.

I just wish I had gotten patents for the things I worked on in grad school, even if those patents belonged to the university.

These days I strongly advise young people to just get a bachelors and forget the rest unless it's required (e.g. for teaching).