There's no denying that some are like this. I have friends who seem absolutely impervious to facts once they have an idea in their heads. But even they can be worked on over time. And most people aren't like this.
I've seen over and over again, even in the comments here, how ready people are to believe that every Tump supporter is a sub-human moron who can't be reasoned with. Who could be surprised that when treated like this, these people run into the arms of any scumbag who doesn't tell them that they're stupid and their concerns don't matter?