I think it depends on how you define the "hobby"-- if it is the ongoing quest for improvements in sound through the acquisition/change of equipment, tweaking and room positioning, you could conceivably do that endlessly until you run out of funds or get frustrated and/or say "good enough." To me, gear acquisition and improving the performance of a system in a given room is but one part of the hobby- the other has to do with learning more about different music, its history and being exposed to different performances.
I was very caught up in the "high end" at a young age- and had already built quite a good system by the time I was 20 years old- all ARC electronics, Quad Loudspeakers, SP-10 table, etc. I augmented that over the years with ribbon tweeters and subs, and migrated to Crosby Quads, with a continuous procession of ARC tube electronics. During that period, I was mostly listening to "audiophile" recordings, and focused more on what was wrong with the system than just enjoying it for what it was.
At some point during a hiatus from audio- I didn't even have a good system set up at the time, all was in crates, but had a roomful of records in boxes--I decided to go in a different direction, started to curate the records I had and search out better copies of all sorts of things. I had a substantial collection of classical and straight ahead jazz, along with a lot of rock warhorses, but dug pretty deeply to find the vaunted pressings, which led me into the collector's market and that exposed me to a whole other world of music, including deep prog and avant-garde jazz. I started building a new system from scratch in around 2006. I made running improvements through the time I moved full-time from NY to Texas in 2017.
I'm at a point where I'm very happy with my main system (and set up a vintage system that replicates what I ran in 1975, using some of the exact same equipment I kept from more than 50 years ago). And though I was on a tear in buying up obscure and collectible records, I've slowed down considerably, due largely to grade and price inflation. I still buy, but I'm very selective, and there is very little I really "need" or want.
I do not think of this as an "ending" but instead, a transition that was long in the making--being able to enjoy what I have. Yesterday, I played a couple of discs from the Art Pepper Live at the Vanguard and Shelly Manne Live at the Blackhawk and reveled in what I was hearing. To me, the end of the equipment quest was in some ways the beginning of my understanding of the music and the performers behind it.