Different Worlds.

People self-select into bubbles along all sorts of axes. Some of these bubbles are obvious and easy to explain, like rich people mostly meeting other rich people at the country club. Others are more mysterious, like how some non-programmer ends up with mostly programmer friends. Still others are horrible and completely outside comprehension, like someone who tries very hard to avoid abusers but ends up in multiple abusive relationships anyway. Even for two people living in the same country, city, and neighborhood, they can have a “society” made up of very different types of people.