Can confirm, I'm one of those people. I mean I had an account on a Mastodon instance before that, but it became my primary social platform when Twitter got taken over.
non sequitur. The point is that "everyone" left Twitter is nonsense; no one said that no one did. Mastodon and Bluesky are alternatives, but Twitter is still dominant despite all the Nazis there.
I know a considerable number of people who abandoned Twitter for either Mastodon or Bluesky and haven't gone back. It probably depends on what circles you run in. There are some people I know who keep Twitter accounts because it's used for professional networking, for example, but they're in specific fields.
People (correctly) bag on Bluesky's mod team (it'd be awesome if they just stopped doing boneheaded shit but that's a complaint as old as USENET...) but I have thriving communities there. I post, I respond to posts. I don't get 17k likes but I don't especially want that anymore. I like small social media and Bluesky delivers.