I think it comes with age. We all have many years of experience with this stuff, and I'd say gaming is my most consistent hobby. Since a kid I've played the hell out of them, and now adays it seems they're nearly a waste of my spare time.
Imagine all of the time we spent on this hobby and put it towards something more beneficial..
What exactly is something more "beneficial" though? You mean like working at a charity or something? Or just doing something different to keep you entertained?
Almost everyone I grew up with and my peers I think leave pretty boring lives. Work 9-5 at a desk, raise a few kids. No travel, no reading, nothing intellectually stimulating.