I think that you are severely overestimating the number of people who believe the political bullshit. A much simpler explanation is that the vast majority are simply lying about believing it. How would American right-wing voters behave if they actually believed that the election was stolen? They would boycott voting and they would do it loudly. But they don't actually believe it.

There is a word for this type of lie: vranyo.

Lying about believing that Trump will build a wall and make Mexico pay for it distracts you from addressing their actual motivations which they know are cruel and unjust.