Yeah.
According to this site: https://usafacts.org/articles/what-percentage-of-the-us-population-is-transgender/ about 1.14% of the US is trans.
And according to https://en.m.wikipedia.org/wiki/United_States_Armed_Forces there’s about 1.328 million active duty armed forces in the US.
1.14% of 1.328 million would be 15,139, so 15,000 is pretty much exactly in line with the typical stats. I wouldn’t be at all surprised if it is in fact an estimate based on such data, rather than there being a survey ready-to-go which identifies how many such service members there are.
Because they didn’t turn on federation until last year, and at that point it was still limited to fewer than ten users per alternate server, and you had to manually request federation through a Discord server from an actual human. This year they’ve automated the federation process, but you still have to start with a tiny server, and they claim they’re going to raise the user limit gradually as new servers remain federated with the main server.
But yeah, the upshot is bsky.social has 13 million users, and there are no other servers with notable numbers of users. That’s a pretty notable difference from ActivityPub.