The point about people coming and not staying cause they see the bitcoiners and whatever else might be true for folks just wandering in. I just think those people just prefer the centralized social media alternatives since they are well established and have a huge amount of content.

It's a bit different if an entire community tries to move to a platform/protocol though. Like many FOSS users moving over to Mastodon from Twitter and to Matrix from Discord in order to follow their "leaders" and peers. I would guess that those bring the huge numbers and cause people to stay.