> A PhD makes sense at any age for happiness reasons if you don't have financial obligations hanging over you. Conditional on actually wanting to go that deep

> A PhD makes sense at any age for happiness reasons if you don't have financial obligations hanging over you. Conditional on actually wanting to go that deep in courses and research. Many PhD students take a couple semesters of courses (the hardest year of their life) and they quit after they realize the research they're going to be doing for at least the next few years. It's certainly not for everyone.