Believe it or not, many people go to college for more than credential-seeking or vocation. Some people want to develop intellectually. Others are more or less set—either financially, or with the vocational skills they developed in high school—and would like to pursue philosophy with their career already lined up.

A formal education in philosophy at a good R1 school is not comparable to light reading by an amateur. The process of discussion, argumentation, and mentorship is not something you figure out yourself. Even an undergraduate degree is a huge step toward a philosophical education. I'm not sure it can be replicated in a vacuum. And it's certainly not easy (first time I've heard that).