That is not the way the history of online social networks has played out. It seems pretty well established that most people want to be where all the action is,

That is not the way the history of online social networks has played out. It seems pretty well established that most people want to be where all the action is, and that niche groups will never be the primary form of social interaction, even if they will always have a role to play, that will be bigger or smaller at various times. I am not making a qualitative judgment, just stating what to me is an established social fact. I personally avoid almost all social networks - especially fb, twitter, insta, and tiktok. But most everybody gravitates to them for various reasons, and have always sought out these big sites as far as I have seen.