I've never understood the argument that getting a PhD is worth it because education is worth it on its own. The premise is correct, but the conclusion doesn't follow. A PhD used to mean a qualification you had to get for a specific set of jobs or careers, now a lot of people argue for it as some culturally enriching experience. If you look carefully at this assumption it masks a pretty insidious elitism, which is that you can only truly appreciate culture and art via qualification. This is bogus. As Will Hunting said,

https://www.youtube.com/watch?v=6ZI1vgJwUP0&t=2m25s