What do you mean when you say "privacy"? Threads isn't more or less private than using any other federated service-- they all share everything you do on them with everything else anyway. I guess federation doesn't share things like your email and IP address, so there is some privacy-related concerns, so maybe that's what you meant?

The big distinction between threads and, say, Mastodon is that Mastodon doesn't have an algorithm. The minor distinctions are more along the lines of it being open source and not controlled by a giant corporation. I am not surprised that most people don't care about (or maybe actively seek out) a service with an algorithm, let alone about the benefits of FOSS.