Hunger drives people. For some it's the hunger for financial safety to cover their needs (housing, food, etc.), for other it's the hunger for being better than your previous self, or better than your peers/competition.

Truth be told, if you're all set in life - financially independent - and don't need to produce anything, it is incredibly easy to just become another dilettante.

Actually pursuing hobbies full time takes some serious discipline, because you really don't have any commitments - and can quit whenever you want, without any consequences whatsoever.

And, thus, for the vast majority - focusing on hobbies full-time can become a chore. You rarely (if ever) hear about retired rich people that become the very best in some field they see as their hobby.

At least with work, you have clients / customers. It's much easier to tell your boss "fuck you, I quit" once you have that kind of money - than to quit on your paying clients/customers.

Also, and this is just my observation, people seem to become (intellectually) duller real quick after they retire and don't do anything specific.

It’s not just a matter of commitment with hobbies either. I like Dream Theater and I play electric guitar. But try as I might I will never even come close to John Petrucci. It’s not even physically doable, although I’ve gotten pretty decent over the years. Whereas in my professional life I _am_ at the top of the food chain if I want to play ball. I just sometimes struggle to find an interesting game to play so to speak.