Trump the person, not the particulars of his agenda, drives the Left crazy. It is not just that he can be crude, blunt, and uncouth, but that by doing so he delights the half of the country that is sickened by supposedly elegant political correctness.I'd add, a lot of what drives people crazy about Trump is a social class issue. Democrats and many Republicans respect "old money." FDR, the Kennedy brothers, the Bushes and John Kerry come to mind. If you don't remember, Lyndon Johnson's crudity frankly offended them.
If Trump’s political agendas so far are correctives of Obama radicalism, his cultural and rhetorical agendas — Americans first, nationalism in lieu of globalization, economic and military rather than soft power, confident American ascendance rather than slow and comfortable adjustment to decline, the melting pot over the salad bowl — represent to the Democrats heretical apostasies from the entire politically correct national faith.
Trump is, or at least acts like, "new money." Terms like arriviste seem to fit. Trump talks and acts like most people would act if they made a whole pile of money and weren't accustomed to it. He has the "I made it, why can't you?" attitude common to the self-made, instead of the noblesse oblige attitude of old inherited wealth.
The snobbish can't stand his perceived "lack of class," his involvement with tacky wrestling, beauty pageants, and entertainment. Such people, they believe, belong in People magazine, not in the White House. Maybe you agree, if you are a closet royalist.