The Leftists believe that they are self-evidentally correct. Therefore their opinions are facts, self evident facts, indisputable facts. Therefore, everybody actually agrees with them. If you don't acquiesce to their beliefs, it must be because you are crazy, or have ulterior motives, or are evil, probably all three. Which is why they put opposition to their beliefs in pseudo medical terms: homophobia; islamophobia; Trump supporters certifiably crazy; and so on. However, being ‘sick’ does not relieve their opponents from moral reprehensibility; there is no ‘not-guilty by reason of insanity’ is their mind set. Quite the contrary.
Naturally, they cannot allow crazy, corrupt, evil people to have any say. We can't be allowed to govern. We must not be allowed to speak. Our very lives, liberties, and pursuits of happiness are at their sufferance only; and, they believe, they have suffered enough. They won't put up with us anymore.
Sadly, this point of view is not confined to the Left, but it is the Progressives who are out in the streets rioting at this time.