It's the bubble they are in. These leftists always stay in their bubble where they get sycophantic praise from everybody around them. As a result, they often forget that there is a whole nation out there of people who think differently, so they get sloppy.
Hillary had to learn that the hard way.
You think that Herself learned ANYTHING by the humiliation Herself has gone through since October 2016?
It may have been the hardest way of all, but learning a lesson of value? Neva happen, GI.