There are many already. The code is not why people use those sites. In the case of Meta specifically, it's basically in spite of the user-hostile, garbage code.

The network effect / entrenchment means that any replacement has to be massively better in every dimension to have a chance. Otherwise people just stick to what they know, and then other people stick to it because the other people do. And so on.

I personally think Musk is a garbage-tier human who represents everything wrong with culture wars, and his brain is long blasted into a mush of worthless racist noise and stupidity by drug abuse, so I deleted my X account. Loads of others are too cowardly/selfish to do so.

Or they just disagree with you.

I believe Musk might be a decent person. He is obviously smart, but perhaps he fears foreigners too much.

X is decent for getting the latest news. The comment sections are often filled with garbage, even more so than Reddit. Ads are hard to distinguish from normal posts. There is a lot of bots in the comments.

I think people try alternatives, turns out to be a ghost town, then they just go back.

People really do not want to give up the reach once they have tasted it.

It’s a shame: I remember when people would be so excited to get 100 strangers visiting their blogs but in a month, but now someone blogging for an audience like that would seem a little crazy, maybe paradoxically even overly grandiose.

Also, the harm from using X is complex. It basically comes from endorsing the site and encouraging other people to come there where they’ll be exposed to a cesspit of bigotry and right-wing ideas. It’s easy to tell yourself that what you’re doing there outweighs the cons, and that other sites are just as bad, etc.