Pre-covid, I think there was a lot of misinformation and people stuck in idea bubbles, where they hear something that makes sense to them and then find a group that agrees with said thing, Once theyre in the group they just have this like positive feedback loop between them all, so its hard for reason to break through.
Post covid its the same thing, but now wrapped up in identity politics, where people asscioate their identity with what side of the isle your on.