LOL this is the answer. For better or worse, the Fediverse has a large established culture. I would not fault someone for trying out every possible alternative first.
Is it really crazy? Most users don't give a shit about the tech or politics, they just want to go where the people they are interested in are, and most of them don't care either! Bluesky is actively promoting itself as the new old Twitter, so that's where people who want that are going.
I have a mastodon and honestly, it's hardly a replacement. different instances are far too isolated even when federating together. Finding user accounts is difficult, and basic stuff like seeing content on another instance is needlessly kneecapped compared to other ActivityPub stuff like Lemmy.
It's unfortunate, but regular people don't want to learn about new things and just want one platform where everybody is, basically "Twitter without Musk".