TL;DR : Trump is a 'mixed bag' but for right wingers the cost-benefit analysis surpassed that of Hillary Clinton, even though there were heavy costs.

I'm not sure we should be delving into politics on hacker news. But if it's okay for the goose, allow the gander to retort.

I hear you expressing your frustration and believe me I am fully aware that many Americans are very frustrated. Especially people on the left who have suffered a series of depressing defeats. On an emotional level, I'm worried and empathetic.

I think you are correctly recognizing certain behavioral characteristics of Trump that are unpleasant and possibly harmful such as lies, bragging, and narcissistic behavior. Many (probably most) people on the right who voted for him also see those characteristics. They are as you say "completely obvious." It is not that people on the right are "blind." So the question is why did they vote for him anyway? Why wouldn't these characteristics rule him out?

Your conclusion is that they are (if not blind) dumb. That might be true for some people, but it cannot possibly explain it for everybody. Take myself for example. I have had my IQ tested three times, and the lowest value was 147. I would say that objectively speaking I am not dumb. I must qualify this with the fact that I was a child all three times so there was a correction factor involved which would not apply now, so my IQ is probably lower today. I hate to put this paragraph in because it sounds like bragging, but I need evidence to demonstrate my point.

Here is part of the answer to the mystery we are presented with:

1) Trump did in fact do very well in business, contrary to various articles that argue he would have done better in the S&P500.
Their calculations are off because they don't value his business as a going concern, did not apply top tax rates to the
dividends, and often picked the market bottom which is unfair as nobody can time the market. The methodology was flawed
because it is a sector comparison (stocks to real estate). The conclusion is flawed because it presumes being on par with
the S&P500 is what "any idiot could do in an index fund" but the proper conclusion is "being on par with the very best
companies" because it's not sharing in someone else's created wealth, it's actually creating the wealth.
EDIT: I forgot to add, they completely ignored expenses.
2) Trump's lies are mostly inconsequential bragging. Everyone can see through them. Successful deception would actually be
damaging, but unsuccessful "first grader stuff" isn't damaging because we can all see through it. We know full well why
he lies in most cases (narcissism or negotiation, in both cases we are okay with it). Also, we like that he just says what
he thinks openly rather than being careful with his words which makes us suspicious of dececptions that we might not be able
to detect.
3) He has openly promised things that right-wingers want and have been pounding the table about for generations. And we believed
he was serious about it and wouldn't let politics or being politically correctness get in the way. We were right, he didn't.
He just storms ahead damn-the-torpedoes, ignoring the news, ignoring the 'game'. Most republicans would have restrained
themselves based on political chicanery. Right-wingers love it and left wingers hate it because he is "unmitigated."

I'm going to stop there because I don't want to write a diatribe.