It's not much of privacy I'm concerned about as much as community and visibility.
Meta is infamous for fostering insufferable users, meanwhile from what I have seen from kbin and lemmy, there is a lot more nuance and maturity in the communities here (for the most part) that I would hate to see overun by Thread users.
Secondly, it's one thing to be visible to the internet in general, but to have anything tied to Meta that they can scrape and sell is a concern to me. The fact that the fediverse is a prototype with vulnerabilities makes the likelihood of a company like Meta, who intentionally exploits vulnerabilities to harvest data, all the more likely.
Finally, almost every example of a large company joining a federation always ends with said company cannibalizing the federated networks, and I have no reason to believe Facebook won't do this. If I'm going to invest time and effort into making a community grow, I would rather not waste my time on a platform that is doomed to be consumed.
be_excellent_to_each_other