I’m learning the opposite lesson. The US is surprisingly fragile and a single president with no morals or ethics can do far more damage than anyone could have imagined.
It's a lot more than "a single president". It's the two thirds of American voters who either voted for him or couldn't be bothered to vote against him, even after having seen how he behaved in his first term.
That's why he's not the biggest problem. He's more of a symptom than a cause. He won't be around for ever, but even after he's gone, most of those same people will still be around.
He largely put that group in place in the executive and the judiciary.
Without populism, he'd have nothing.
It's true that he 'duped' them, but we're all duped on some level.