Nerds, geeks and general outsiders like and look for things like Mastodon and the fediverse, the majority of people just want convenience and ease of access and things like Twitter and Threads have that. Until celebrities and companies join the fediverse you won't get normal people and at that point it won't be any different from Twitter. I like Mastodon but it has nothing on the ease and just general amount of everything that Twitter has which is what brings in users.