There are many factors coalescing to remove the leash which has usually but not always restrained leftists' impulse to go full guillotine. When that leash is loosed, The Black Book of Communism documents for us 100 million examples of that impulse.
Why do leftists have this impulse reposing within them like a virus only waiting to emerge opportunistically when they sense they are unleashed? To answer a question about first principles one should go to the original source. The first books of the Bible tell us why, because they would be God.
What are the factors that have coalesced to energize this virus? Nathan Bedford's first Maxim of American politics: all politics in America is not local (as tip O'Neill would have it) but ultimately racial. Leftists have cornered the market on allegations of racism which means that they, by definition, win every argument. It means that they have immunity from criticism, especially in the media which means that they are almost never held to account. Why has Donald Trump then the victim of a hoax for two years while Hillary Clinton was corruptly exonerated for her felonies? Because a different standard applies, and that standard comes from the basic presumption that Republicans are bad and Democrats are good and that is because Republicans are racists and Democrats are not.
Recently as we all know, homophobia, gender inequality, tribalism, and bigotry have been added to racism as new weapons of slightly different caliber to immunize the left and demonize the right.
Academia has contributed a weapon to further marginalize the right, "critical thinking" which has morphed into its antonym, "uncritical thinking" or political correctness which requires unanimity of thought bordering on that of a cult. With time, academia has fed all our other institutions including the media, the courts, our banks, and our churches with generation after generation of uncritically thinking leftists who, because of Nathan Bedford's first Maxim of American politics and its sequelae have arrived at a level of arrogance which permits them to feel safe, to unleash the Jacobin impulse.
Throw in George Soros' money (always follow the money) and that of Wall Street and K St., and the power of the cult becomes complete with no chance for the host of the virus to even understand much less curb his lust to be God.

“With time, academia has fed all our other institutions including the media, the courts, our banks, and our churches with generation after generation of uncritically thinking leftists.
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Good comments overall but in particular the one above. Academia is the wellspring of liberalism. But its even worse than that; academia is not only producing and enabling radical leftists, it is now turning a blind eye toward their increasing intolerance and extremism.