People do it for the community. The right wing has done it because they’ve been more or less pushed out of normal culture because of how awful they’ve become. Same reason conspiracy theorists stick together. At least with sports there’s a winner and loser and it mostly can’t be disputed or ignored.
The don’t talk about politics and religion at dinner thing is very true. No one wants to leave their house and be miserable.
So what, nuke it and start over? How do we destroy the bacteria and still have the majority of our walls standing?!