that's also partly because of Fox News, which was explicitly founded to ensure that the next Nixon would survive his Watergate.

This is true, and it's probably because he now operates in an altered context — the narrative of persecution, especially by those perceived to be 'elite'. Without that, all Americans would see through his nonsense just as the inhabitants of democracies elsewhere do.

His opponents have done a very bad job of not making it look like everyone's simply biased and out to get him, and he's capitalised on that.