You might be in some kind of bubble or assuming a lot about strangers based on your own experiences. Lots of people authentically and personally choose to be atheists after being raised within some kind of faith and coming to the conclusion that it is not something they believe in. Others like me were simply raised without the influence of any religion and it all just seems absurd. It’s not being edgy or any kind of performance, perhaps it was for some people you’ve known, but I imagine for most it’s a personal choice (or lack thereof) that they have no reason to tell you or anyone else about or broadcast in any way because the entire enterprise is meaningless to them and really just isn’t something they even think about very much.