-He's a convicted felon
-He was found guilty of raping a woman and also subsequently defaming her
-He demonstrably tried to over-throw the will of the American people to remain in power
-He's offered to gut environmental laws in exchange for $1B from Oil & Gas
-He wants to tear down the most successful military alliance in history that has benefitted America immensely
-He is unable to distinguish between a cognitive test and a I.Q. test
-He's promised legal and physical retribution on people that disagree with him. Or simply don't show sufficient obsequience.
-He would rather believe a hostile head of government over American intelligence analysis
-He deems any sort of personal sacrifice to be a mark of being a loser; not fit to lead US Armed Forces
-He put his own betterment, usually financial, at the forefront of any choices as president
-etc. etc. etc.