There are a lot of reasons and motivations. But, for me, it comes down to one thing for one reason. It's just plain stupidity, pure and simple. I say that because when supporters back a president who plainly doesn't give a damn about those supporters or their lives, that's just plain foolishness to the Nth degree.
Why do I say that? Many of Trump's supporters are non college educated white males who live in middle America and who have felt economically left behind since the great recession of 2008 which decimated their lives while banks were bailed out. I can totally understand that resentment However, Trump has spent his entire life not caring one whit about people like them at all. What Trump has cared about for decades is a short list. What Trump cares about is the following: people with a lot of money, famous celebrities of any stripe, beautiful women, and media attention when he can bend it to glorify himself in some way, regardless of what is and isn't true To that end, Trump is a person who has wholly embraced the old Nike advertising mantra that "Image is Everything." In other words, for Trump, if the truth is not so complimentary, he creates a fiction and sells it to anyone who's willing to buy it. The recent release of his taxes shows that to be true because it shows that he was a poor businessman who lost millions of dollars over several years. But what was the image he fostered to anyone who was willing to listen? The image was of a hugely successful businessman who made billions of dollars.
The bottom line is that Trump is a con man who cons everyone about each and every aspect of his life.