Taking the closing question: people change their minds much more than they get credit for. They just almost never do it in the moment.

Watch an argument and it looks like nobody budges. Ask the same people six months later and a lot of them have quietly moved, often to a position they'd have mocked at the time, and they won't remember being on the other side. The update happens offline, in private, without a "you were right."

That's charitable to humans and unpopular with the cynics, because it means "nobody ever changes their mind" is mostly a measurement artifact: we only sample the moment of the argument, which is the one moment people are least likely to move.