"Dilbert" creator Scott Adams sums up the situation nicely.
How To Know You’re In a Mass Hysteria Bubblehttp://blog.dilbert.com/post/164297628606/how-to-know-youre-in-a-mass-hysteria-bubble
History is full of examples of Mass Hysterias. They happen fairly often. The cool thing about mass hysterias is that you don’t know when you are in one. But sometimes the people who are not experiencing the mass hysteria can recognize when others are experiencing one, if they know what to look for.
I’ll teach you what to look for.
A mass hysteria happens when the public gets a wrong idea about something that has strong emotional content and it triggers cognitive dissonance that is often supported by confirmation bias. In other words, people spontaneously hallucinate a whole new (and usually crazy-sounding) reality and believe they see plenty of evidence for it. The Salem Witch Trials are the best-known example of mass hysteria. The McMartin Pre-School case and the Tulip Bulb hysteria are others. The dotcom bubble probably qualifies. We might soon learn that the Russian Collusion story was mass hysteria in hindsight. The curious lack of solid evidence for Russian collusion is a red flag. But we’ll see how that plays out.
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1. The trigger event for cognitive dissonance
On November 8th of 2016, half the country learned that everything they believed to be both true and obvious turned out to be wrong. The people who thought Trump had no chance of winning were under the impression they were smart people who understood their country, and politics, and how things work in general. When Trump won, they learned they were wrong. They were so very wrong that they reflexively (because this is how all brains work) rewrote the scripts they were seeing in their minds until it all made sense again. The wrong-about-everything crowd decided that the only way their world made sense, with their egos intact, is that either the Russians helped Trump win or there are far more racists in the country than they imagined, and he is their king. Those were the seeds of the two mass hysterias we witness today.
Trump supporters experienced no trigger event for cognitive dissonance when Trump won. Their worldview was confirmed by observed events.