Mine was a gradual stray away, and I think similar to most people's reasons.
Around 7 years ago I started streaming on Twitch casually and I absolutely adored it. I'm chronically ill and unemployed so it can be hard for me to find hobbies that I can endure for long periods of time physically, but once I discovered streaming I was live for 8 hours a day 5 days a week with Stardew Valley. The experience sort of started going downhill after I hit affiliate status and made more connections on the site, though. That thing that I hate, the whole mentality shift of "I can make money off this so now I have to be the best at it and continue to make money off it" got it's claws into me. It's not as bad as it once was, thankfully, but my streams were a huge portion of my income for a long time, so when I took a break for mental health purposes and then returned to basically zero community, I was pretty disappointed despite understanding the logic behind it. I still stream occasionally now, but the many other negative experiences I've had within streaming communities and my gaming burnout, AND my fatigue make it a once in a blue moon kind of situation.
As soon as my brain allowed me to make that disconnect from Twitch, everything else just sort of fell in to place with it. I have zero interest in Instagram, I'm from the generation that used a lot of Facebook until we all got the ick from it and I haven't thought about using it in years. The most I'm active on is Discord, and I consider that less a social media myself and more just another version of forums since I cater the spaces I'm in to have that slow-paced, relaxed vibe.
I recently joined SpaceHey (I discovered it and joined while I was waiting for my account to be approved over here, actually) and I think it's pretty neat but I also feel like I'm going to fall off from that, too. Either that or do a friend list culling lol, I'm an adult so only really accept friend requests from adults in these spaces but even that hasn't stopped the high school-eque vibes and drama my eyes are witness to on the Bulletins over there. Not that people shouldn't have an outlet for these kinds of things, but it's no longer in my interest to consume the woes of the average internet user without meaningful discussion. I realise I probably sound like a bit of an ass here, so I feel the need to point out that in the same years of me distancing myself from social media, I've done a lot of healing and growth with my mental health, and I'm now extremely picky about what I will tolerate and read/consume on a regular basis, and you should be too reader!
Combine these social experiences with the influx of AI, my age getting higher so nostalgia creeping in alongside it, the monetisation monetisation monetisation.. corporations.. branding.. nothing is authentic anymore we are trapped let us OUT.. yeah I just kind of reached a breaking point and found my way here :')
This was my most rambly post on here yet, but it's why these forums are so special to me. I would rather sit and spend ten minutes pondering a question that actually interests me, and then read through the responses to that and formulate my own response, rather than a one and done sentence interaction that leaves me and the other user with nothing.