...the reality being that the gap between "practice your craft relentlessly, and also hustle for gigs and self-promotion endlessly" and "accomplished and successful enough as a musician to comfortably, idly spend all day screwing around on whatever musical idea, with no particular stakes" is vast and the opportunity to bridge it is a window that, at my age, is pretty well closed.
Which I'm mostly OK with. If jam sessions are ever a thing that feel safe again, I expect that about 85% of my "coulda been a contender" itch would be scratched if I can find a good one. I'm still sad about the jug band jam I found out about literally a week before lockdown started last year.