I use twitter to follow content from mostly public people like sports writers, tech writers, some athletes, etc. Effectively, I use it to get breaking news about some things I care about and only rarely interact when I come up with something I think is really funny. Maybe not everyone uses twitter like me but most probably use it to follow famous people and public figures and attempt to interact with them or whatever.
Mastodon can compete with Twitter on a technical capabilities front but its going to struggle to get the mass appeal that Twitter has without the less anonymous clientele.