At least Krauthammer had the guts to oppose Trump, which puts him above about 95% of conservatives.
"(Trump has) a shocking absence of elementary decency and of natural empathy for the most profound of human sorrows -- parental grief.-Charles Krauthammer
[H]e can't help himself. His governing rule in life is to strike back when attacked, disrespected or even slighted. To understand Trump, you have to grasp the General Theory: He judges every action, every pronouncement, every person by a single criterion -- whether or not it/he is "nice" to Trump.
Trump's hypersensitivity and unedited, untempered Pavlovian responses are, shall we say, unusual in both ferocity and predictability.
This is beyond narcissism. I used to think Trump was an 11-year-old, an undeveloped schoolyard bully. I was off by about 10 years. His needs are more primitive, an infantile hunger for approval and praise, a craving that can never be satisfied. He lives in a cocoon of solipsism where the world outside himself has value -- indeed exists -- only insofar as it sustains and inflates him.