I think it is called the network effect. People are still using Twitter because the messages they want to see are being posted there, and those messages are being posted there because that's where the audience is. So, basically, people are locked in.

This also means that any loss in user count has a double effect, as not only users are lost, but the utility of the service for the remaining users decreases. So, what I'm saying is, if Elon continues this way, at some point there will be a large exodus of users from Twitter, as each loss of users reduces the utility of Twitter further, triggering a chain reaction.

Of course, we can't know when that happens, and since we're both on Lemmy, we've already self-selected as people with little tolerance for enshittification.

Porn... Until enough adult accounts move over to Mastodon or Blue Sky.

Well Twitter is still used by Musk fanboys, right wingers, from people who don't understand Mastodon and/or the Fediverse and probably from people who use it for porn.