Mastodon has no privacy at all. Even if you host your own instance. People use Mastodon for freedom and to get away from manipulation by corporate social media.

That's not quite right. Mastodon does not have any privacy at all and it's not safe to treat it as privacy platform.

What makes Mastodon worth using is the federated model and lack of commercial engagement algorithms.

Threads is garbage. You get one page of the people you subscribed to and then the next one is random promoted accounts that might be popular or whatever. The algorithm has more of a chokehold than it does even on Twitter. They can inflate their numbers by saying everyone with an Instagram account has Threads, but I'm not so sure people are actually using it.

Whatever one might say of BlueSky, it shows me the posts of the people I chose to follow, which is the whole point. Mastodon would be better in principle, but most people I follow don't use it so it doesn't do much for me.