Trump is essentially a Trump supremacist, living in a Trump-centric fantasy and valuing a Trump First approach above all else. The rest of his opinions and positions can be changed on demand for the highest bidders, as long as those bidders are willing to serve the Trump First philosophy.
He sees the world as divided into two groups of people: the Trump loyalists on one hand and the traiterous enemies on the other. If you aren't actively supporting him and praising him, then in his eyes you are actively working against him by default and you must be punished appropriately. Sometimes a few disagreements is all it takes for someone to go from being a 'fantastic friend, the very best' to becoming a 'horrible person, absolute scum' in the Trumpiverse. This is especially true in his role as President, because 'Do as I say or I'll fire you on the spot' isn't nearly as effective in the political world as in the corporate.
Trump First is why, for example, he could focus his travel ban on Muslim countries, and at the same time he has no problem working with Muslims if he thinks there is a good deal to be made for him personally. There is a reason Saudi Arabia was never part of the travel ban ..or why he'll try to make himself appear anti-Communist by tweeting against China, while simultaneously verbally fellating North Korean leadership to give the impression of being a political strongman. Life is one big photo op for Trump. He'll do whatever he thinks it takes to make himself look good, and he fully expects everyone else to work on making him look good as well.
This is the biggest difference between Hitler and Trump. Even though Hitler also suffered from delusions of grandeur, he actually believed in all the dumb shit he was preaching. He also sought to surround himself with people who didn't necessarily agree with every single word but who at least shared a common political and racial philosophy with him.
Meanwhile, I highly doubt that Trump honestly believes, for example, there was massive voter fraud that cost him the election. Yet insisting on it over and over again serves the Trump First philosophy in 1) it gives him a reason to keep from conceding and admitting that he lost, 2) it's a way for him to continue to 'piss off the libs' and even Republicans who do not believe in the voter fraud, and 3) it is part of his strategy for him to try to stay in the spotlight as much as possible for the foreseeable future. ..at least until he finds something better to serve Trump First than the possibility of a run in 2024.
Trump has a bridge to sell, and people are willing to buy that bridge for a long list of different reasons. It's not as simple as dismissing all of them as deplorables or Nazis. Sure, some are actual Nazis, who see him as the means to reach their hopes of a country that is at least a little whiter and more American. There are also those who would like to see an actual wall built not because of nativism or racism, but rather because they think the subject of border security has not been taken seriously enough.
Among them are even some legal immigrants that worry that undocumented migrants could be treated like economic refugees down the road, which they would consider an insult against the legal immigrants having had to spend a lot of time, money, and effort to follow all the rules and come here legally.
Yet the majority of people care primarily about the one or two issues that affect them the most, and many Trump voters don't pay attention to the 2 a.m. tweetstorms from the White House toilet or to most else he says, as long as they have the feeling the economy keeps improving. ..or maybe they're someone who's job is on the chopping block, and having a president speaking out against outsourcing to China gives them a certain comfort.
True, some support him mostly because they worry that all the disinformation with which they are bombarded on social media and by Trump himself could be true. Biden might shut down the economy and let the Chinese/Cubans/Venezuelans take over. Harris could lead BLM-sponsored riots and put white people into racial reeducation camps. Something, something about Soros and about late term abortions in there as well. Finally, there are the cultists, the true believers who convince themselves that Democrats want to destroy them and Republicans are willing to let it happen. They couldn't care less about anything other than wanting Trump to inflict maximum damage on the legal and political systems, as well as the shifting cultural and social fabric, they see as the great enemy.
So Trump is a lot of different things to a lot of different Trump supporters, and just like with any other group of people, it's too easy to paint them all with the same broad brush. ..but they all have one thing in common, and that is Trump's willingness is serve their varied interest is limited to only furthering his own interests and the philosophy of Trump First.