It seemed for some people to begin to constitute their "real" life.
100% jiving with my lived experience.
This can be usefully linked to "Feel slightly called out as most of my hobbies are in some way ‘dissociative’"
Gaming etc as part of a balanced life-system and psychological-needs system, where everything's calibrated and interacting in a way that results in an adequately functioning organism in the world = absolutely fine, no problem, stop worrying.
But if something upsets the equilibrium, and internal and external pressures don't allow it to be restored - net result = spiralling unhealthy coping mechanisms, reduction of real world functioning, may or may not eventually find a new workable equilibrium. Doom-loop, basically.
What I saw in fandom (I basically lived there throughout the 00's) was this: people whose equilibrium was already precariously balanced or actively doom-looping, finding a coping mechanism and then doubling down on it when things in the real world got hard.
We all made a claim to the "healthy coping mechanism" label, but for some of us this turned out not to be as true as we thought.
People who were already so far out of equilibrium that they couldn't integrate well enough with the outside world to get their psychological needs met and thus have a chance at minimising doom-loop issues were pulled further from being able to integrate with the offline world. Because the coping mechanism itself was worsening the difficult issues they'd adopted it to manage.
I spent a few years out of fandom and when I went back they'd all lost the plot and drunk the kool-aid, and a lot of people I cared about and felt a strong group-identity with are now identifying as queer and unwittingly bullying lesbians and reinforcing patriarchy and so on.
So it turns out, fandom wasn't an acceptably healthy coping mechanism for a lot of the people who were drawn to it. It felt healthy in the short time but for some people it has the seeds of a massive long-term problem built in.
I do tend to put them in the realm of opinion somewhat though, more like armchair psychology.
Point noted, but when I started the thread I was operating in the realms of 'analysing the patterns in the data we have available.' I acknowledge the current lack of robust scientifically-acquired data; there is merit in analysing the currently-available data nonetheless. And our real-world experiences of whatever phenomenon we happen to be talking about = data. Its acquisition didn't follow the principles of the scientific method but it is data nonetheless and thus may be analysed usefully.