This is what the American public wanted. America isn't a banana republic where the population has no agency. Americans actively went out and voted a convicted criminal in as president.
Only 30% of americans voted for him. Yes, that's quite a share of people ready to vote for a convicted criminal, but not to the point where I would say that the U.S. population showed actual agency in this election - and that might be the crux of the problem.
I take that the non-voting population thought they'd be fine either way. Or just the same either way. Now why would they think that, there might be more answers than I can imagine.
My theory was that it was a mental trap of the kind "Meh, he already was a president and the world didn't end so who cares". Unfortunately, right-wing power gets much worse the second time they get the chance to rule.