I think it boils down to what you find more "shiny" during your life.
We folk can be an obsessive lot and it is easy to find yourself sucked into some hobby culture you may have looked at or your friends got into.
I have NEVER come across anyone without some obsessive hobby, some are more traditional than most.
I have always put together models.
It has evolved a bit more toward tabletop but I can put together the odd car, tank, Gundam or battleship.
I still obsess over music and finding much fun in stuff playing on Altnation.
I have two kids and yes, the early years can kill the hobby dead until they sleep more and you can be up past midnight like I plan to do tonight to work on Shadow War Armageddon terrain.
We DO "grow up" but all that means is to attend to the important details and relationships that matter which allow us the time later to pursue our interests and what makes us happy.
Yeah, maybe I should be reviewing my investments a bit better and find better places to put my money.
I review these things but like with any hobby: you draw a line between enough is enough or you are just fiddling because you can (I also like sailing which is a FINE example of constant fussing).
Scuba Dive, Kendo, I cook, I can sew, awesome at Excel... as the years stack up, you find cool stuff to do and never quite leave them behind.
Best quote on this I know:
"We don't stop playing because we grow old; we grow old because we stop playing.
George Bernard Shaw
BTW I am 48 this year, so there is hope OR you can look at it that I am some immature neckbeard

... got a good job, married, my own big house, scary strange kids but I live (when I can) in the basement in my man-cave and I tend to get all kinds of "visitors" to include in my fun.
Automatically Appended Next Post: I would add one thing I noticed:
If many things you used to enjoy no longer work: it may be signs of depression.
Something I experienced, caught me by surprise so worth mentioning.
The social aspects of hobby and finding good people I would agree is a big thing for me too.
One can only stay in the cave so long.