The bullshit artist
It’s important to understand the difference between bullshit and a simple lie. The reason Trump says so much that is grossly false is that he is a bullshit artist, for whom facts are simply irrelevant. This video (youtube) provides an excellent example. Read the story here. Any normal, rational person wonders why Trump would say something so blatantly false. The answer is quite simple. It gives him a talking point that reinforces what his followers want to believe, and what he wants them to believe. That it is fabricated from broadcloth doesn’t matter to him. And it doesn’t matter to them. They both like the fantasy world it complements.