Relative obscurity is an aspect of it for sure, and I imagine networking effects are a big part of it as well. Accounts with a lot of followers tend to drive where people migrate. When a big account leaves twitter to bluesky they can pull thousands or even millions of users along with them. Meanwhile, people moving to Fediverse end up having to abandon a lot of the people they were following as a result. It's also a lot easier for an account to grow on a centralized platform which is another reinforcing factor here.

I think ignorance (in the non pejorative sense) plays a big part. I can't really blame my non technical friends for not fully understanding that ditching Facebook for Instagram doesn't help. Even if they know it's the same company, it's still a totally different product, right? There's also a certain apathy or need to just get something done.

I'm sure I've purchased things at Home Depot that would make a plumber cringe, but I know nothing about that sort of thing and I just need to get my sink working.

Still, I think those of us who do know should continue to lead by example. My friends know my stance on these things and some of them are coming around.