To be fair, more people who voted didn't think he was the best choice of a person "capable of ..." than thought he was. He only won thanks to a) a quirk of the American electoral system and b) his opponent also being historically unpopular, by nature of having been in the public eye on one side of the US political system for 25 years.
I can certainly agree with b) but a) is not a very useful way of looking at things. if you went back and changed nothing else about the election except making popular vote the win condition, hillary clinton would obviously have won. but this small modification would have totally changed the campaign strategy of every candidate. people who didn't bother voting might have voted. donald trump might have won anyway with a different strategy. we might not even have been choosing between trump and clinton in the first place!
not saying the electoral college is good, just that this isn't a strong argument to the contrary.
This is extremely good question that I continue to be unable to find an answer. Much bigger case than Epstein would be that of Donald Trump. Everyone knew he is a six-time bankruptee, posted record $1B (billion) dollar loss with IRS and haven't made any of his many business ventures successful, other than add some to the real estate fortune that his father left him, but nothing too spectacular (growing $400MM to $600MM in two decades, which adjusted for inflation is probably close to zero). Yet the consensus of 2016 was that he is the only man capable of steering forward a budget of the most valuable country on the face of planet Earth. Its boggling my mind, frankly.