[ryandrake]

It might not be that these topics just "don't come up" like it's some kind of accident. When people hold these "weird beliefs" as he puts it, [I think] they generally know they are weird and would be embarrassed to bring them up.

I don't think I know any Flat Earthers, but if I actually do, they probably deliberately keep it to themselves because they know that they'd look like kooks by outing themselves. To get more extreme, maybe some of my friends are Nazis, but they sure aren't showing me their memorabilia, not because "it just doesn't come up" but because they know it's wrong and don't want to ostracize themselves.

Maybe eventually people work up the courage to probe a little, they'll use code words and innuendo, and soft dogwhistles, maintaining plausible deniability until they identify their fellow outgroup members. I think I see this behavior in a few of my friends, but they wisely don't come out with it.