It’s essentially these two things. And it’s easy to see from any political map that these divides line up really well along rural vs urban areas. People who live in cities have learned how to live together and tolerate each other (even if they don’t necessarily like each other). People in rural areas think of themselves as the ‘backbone’ of the country because or our early agrarian and later industrial development as a country. And in many ways, they really were. Farmers, miners, factory workers, etc.
But time has left them behind with factory farms, overseas production, robot factories, renewable energy, etc. They blame “the other” for their problems. The “other” or “the enemy” in their minds is often “big city” people with darker skin, or “academic pinheads” or “government bureaucrats” or basically anyone but themselves. To them, hearing news about something like climate change or same sex marriage is an “attack on their way of life and traditional values”. They haven’t learned how to adapt or take proper stock of their situation. They only know how to lash out at “the other”.
If rural people would calm the fuck down and gain some perspective, they could see that they have a lot in common with working people in urban areas. For example, we’re all being fucked over by greedy corporations and a tiny number of people with way too much money and power. But those same powerful elites do a masterful job of pitting all of us working class slobs against each other. This both amuses them and keeps us divided so we don’t build the guillotines. The country being ever on the brink of civil war is very much intentional.
And of course there are guys like Steve Bannon, who is like a comic book villain. Guys like that really do want to see it all burn to the ground so it can be rebooted in some fantasy world where “bitter old white males like me rule again”.