Close to everyone I know is still on Facebook, and I get the impression none of them have any interest in switching, so... I use it too, even though the algorithmic curation stuff is really bad.
I could imagine people switching if someone made another site with some kind of killer app and promoted it with a million dollars of ads, but... At the moment, the only feature the alternatives focus on is usually privacy, which is clearly not enough to make average people switch.
Network effects aren't the only factor that matters, just a really big one for most.