For all the reasons there are - "The Democrats didn't so much lose touch with the electorate, as the electorate lost touch with reality."
And more disinformation than ever before helped to creat that situation.
Plus the fact that in tough times incumbent governments tend to lose their advantage, and just now it is tough times worldwide.
It was Plato who said, “He, O men, is the wisest, who like Socrates, knows that his wisdom is in truth worth nothing”