You've mentioned something unique about Trump. What you wrote is true, beyond doubt, but the question is "why Trump?" Explanations I can dream up are unsatisfying.
The best theory I can come up with is that we had no immunity to someone who is just utterly shameless and never even considers apologizing. Every scandalous story helps him because it makes people forget about the one from a few days ago. Turns out that’s a superpower in early 21st century America.
That's not an explanation, though. Why are the American people so weak to someone so uniquely awful, evil, mentally disabled and morally degenerate? Is it replicable? Can the next gigabastard just not care too, and the Americans will fall in line? Or does it die with him? What is it about Trump and what it is about Americans?
It's hard for me as a foreign admirer of the USA not to conclude that a small majority of Americans are fundamentally quite venal and nasty. To think that I used to believe that shit Reagan said about the US being a city on a hill! Crazy.
Your first paragraph is exactly right in it's questions. Depending on how successful Trump ultimately is, will his successor be able to continue.
Your 2nd paragraph is hard for me, a US citizen, to see. Reagan was in fact a complete faker and a liar. US religious leaders are also fakers and liars.
The difference now is that prior politicians had at least some interest in actually governing the country. That limited just how viciously they could engage with their political opponents. There was never any golden age of collegiality, to be sure, but even people like Newt Gingrich wanted to at least try running the country in between political campaigns.
And yet there's no immediately apparent runner-up gigabastard. All of the politicians, even Trump's most dedicated sycophants, are still hampered by the notion of wanting to actually run the nation. It doesn't work without a 100% commitment to smashing your enemies. If you let the conversation drift to figuring out valid policies, people lose attention, and realize that you're an idiot.
None of the other tech-bros seem to have it, either. If Musk or Zuckerberg or Bezos run for office, they're going to discover that people don't actually like them. They're smart enough to think that they can actually talk about policy, and nobody really likes policy. They want simplistic, vacuous solutions. Musk has the requisite cruelty to distract people from that, but he's not enough of a buffoon to really entertain the far right.
I can think of several reasons why the US public finds Trump more appealing. Trump is a US national born and bred, whilst Musk was born in South Africa and holds Canadian as well as US citizenship. Trump absolutely nails populist rhetoric, whilst Musk is nerdy and aloof. Trump describes himself as chosen by God and vows to bring religion back to America, whilst Musk is nuanced and cagey about religion. Trump has celeb certification with his appearances on The Apprentice and WWE, whilst Musk tends to avoid mainstream media.