A lot of it these days is rooted in fear. On both sides, mind you, but epsecially on the far right. Afraid of loss of identity, the world changing too fast. And you can't make the world move or change slower just to suit people who think 1955 was the Very Best Time for America(n WASPs).
The World As We Know It is gone, and instead you get a strange new world where men aren't men, women aren't women, black people don't know their place, boys just being boys isn't accepted anymore, and everything seems out of your control. The world is going to Hell (this, at least, pretty much everyone can agree on) and it seems you have no personal control over it. Some might find that they need to stop eating meat and go on a holy Crusade to stop everyone eating meat because that's terrible for nature. Others might need to believe there's a great big conspiracy of child eating pizza molesting rich Jewish democrats. And having a Great Leader to Solve Everything - a Guide to bring the people back to the right path - is...a solution. Whether it's Erdogan or Putin or Orban or Trump, they promise a solution. "Let me handle things, you won't need to worry, I'll stop all those bad things from affecting you. If everyone just agrees to stay in 1960 and keep their head down, we'd all be so much better off".
There's really no solution. People WILL get scared of things out of their control. People WILL look for easy answers. People WILL fall for propaganda. Teaching everyone rhethoric and philosophy and history and media savvy etc might help, but even so. I still see really smart people who KNOW all this still fall into the same pitfalls.