The cause is an education system which set them up to be both emotionally unstable and historically unknowledgeable.
Then the left’s reaction to Trump’s win set off a lot of feelings that they were unable to deal with either emotionally or logically. A little bit of knowledge could have let them move on, but they’ve been trained to reject knowledge that disagrees with feelings.
“The cause is an education system...”
Nah, that’s a contributing factor but bad parenting is much more fundamental.