Interesting observation (which I've read before, but just been reminded of): the #Fediverse is too stale, too serious, too boring.
If you don't want to talk about politics, or religion, or current affairs, or climate change, or -- and this is a big one --anything whatsoever to do with computers or technology or software, you're going to struggle to find your tribe here.
I mean what if you want to talk about #fishing? Or drag #racing? Or #decorating... Or rowing in #kayaks painted in pink with bright blue polka dots?
We have a few tiny communities for each of those things, but they're difficult to find. Whereas X, for example, has enough users that if you search for any of those hashtags, you're 99%+ sure to find a huge, vibrant group of people chatting.
People won't come because we don't have the content they're looking for. But we're unlikely to have the content they're looking for because not enough people are coming over.