@Tristan Nuovo, I make it a point never to argue with a guy who knows his right from his left!

That he doesn't have their interests at heart, only his own.

Anything, just anything.

He displays many Narcissistic traits.

People of low intelligence often believe themselves to be of above-average, or even high intelligence. That goes for extremists of any hue.

I don't think there are things that they don't understand. I think there are things they refuse to believe or don't give a damn about. Not understand implies ignorance in their behavior and I'm not that generous. After 2 years of this con man, if you still don't "understand", then you don't give a damn.

He is the swamp he was supposed to drain...

I only get to pick one? Okay I will go with he is as qualified to be the president as I am to be a brain surgeon! Until becoming president, he had no political experience. I have never studied medical science. Take a vote...

Other than he really isn't of Presidential calibre? Nothing really

Donald Trump mastered this at Wharton.

puffery noun
puff·​ery | \ ˈpə-f(ə-)rē
Definition of puffery
: exaggerated commendation especially for promotional purposes : hype

This is taught at every Business School, usually in Business Law Class. It is also why I made my mom buy me Wonder Bread and Ovaltine as a kid yet I am still unable to lift a car or jump 12 feet in the air.
Donald Trump has taken its use far beyond advertising and deems to use it in every aspect of his life. Listen to his description of the "Wall". "Mexicans WILL PAY for it". " Make America GREAT again." "I have a TREMENDOUS brain". "There has been ABSOLUTELY no collusion between my campaign and the Russians".
Its all as real as the claims of Wonder Bread, Ovaltine, Trump University or a check to one of Trump's contractors.
He's an admitted Racist and Scam Artist with several guilty pleas in court to prove it.

You can't go backwards. Most of what you think about the past is imaginary and the old days are not coming back.

That he is neither fit nor qualified to be president.

That Trump is not and has never been a product of his own making. That he's a 22 billion dollar trust fund baby who has spent his life being propped up by others.

The same question could be asked about the far lefters as well.
Personally I think the far right, and the far Left are both nuts, and neither of them will listen to a thing the other says.
JMHO.