You mentioned "Little Marco", "Crooked Hillary".  Don't forget "Ly'in Ted" (sic), "Low Energy Bush", Not a hero McCain. Childish name calling but it worked for his base.

These are people he personally attacked and many he then expected to support him as President. In the old days, when Congress was less partisan you senators would regularly cross the floor on issues. US politics is toxic.

He expects loyalty but does not give it (except his family - perhaps). Jeff Sessions took a lot of criticism for being a Trump supporter and defended Trump in the media. And when he showed some integrity by recusing himself Mr Trump threw him under the bus. What message does this send to world leaders, business people, and other politicians? You have a president you can't trust.