According to my sister, who's lived in the US for over 40 years, is a staunch Democrat and follows politics closely, it was well on the cards. She blames the Democratic Party hierarchy, who would have Hillary knowing very well that she was unpopular, and was perceived to be (and was) in bed with big business, Wall Street, the fossil imdustry, the Neocons, etc. She thinks it ludicrous that they are now blaming it on misogyny and calling her a victim because of her sex, when she's a hugely wealthy and powerful woman.
Says also that if they'd picked Bernie Sanders (her own choice) they'd have won.
She didn't vote for Hillary, but for a 3rd party candidate, since Hillary was safe in her state (Mass) anyway.
She says it was pretty obvious that vast swathes of the disenchanted who've been left behind would send a great big f* k off to the liberal elites on both coasts.
Shades of Brexit indeed.