I find the puzzlement more than a bit strange.  Europe has had its share of demagogues.  France currently has Marin Le Pen; her father has been around almost forever.  It's true that she was not elected, but she could have been.  If the French had something like our electoral college, who knows how things would have gone.
Hungary has Orban.  Poland's Duda is not much better.  https://news.vice.com/article/polands-right-wing-government-scares-europe-by-going-after-the-media.
Brexit was fueled by much of the same type of rhetoric as Trump used.  I know that May is  a grown-up, not a petulant teen, like our president, but still ....
The racist xenophobia and misogyny that allowed Trump to triumph is by no means absent in Europe.  Maybe Europeans need to turn on the lights, so that they can better see the reflection in the mirror.