How long have you been out of grad school?
If you are still in grad school... Write us back in ten years and tell us how academia is coming along. Meanwhile, carpe diem.
If you're out of grad school, tell us how much more awesome your career is than those of your relatively-untrained peers. More money? More respect? More challenges? What?
I went to grad school, and then I did a postdoc, and these things were indeed very fun hobbies [1], though very very expensive in lost income and opportunity cost. But now I support a large number of PHP apps, make significantly more money than I did as a researcher, have significantly more impact on human lives than as a researcher, work less hard than a researcher... And am, gosh, approximately ten years behind my peers career-wise. Oh, those expensive hobbies!
Still, nothing wrong with having hobbies. Just do be sure to know the difference between hobby and career. It can be similar to the difference between the transient and the steady-state.
And if you're out of grad school and have managed to secure an awesome steady-state career as an academic researcher with job security and good pay and time to spend with your family, your other hobbies, and your community, please do write back and tell us again how arrogant we are.
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[1] In much the same way, I imagine, that the triathlon is fun.