Existential threat

I have never used the word "existential" except to quote someone else. I don't have any idea what it means when others use it. So, I looked it up and here's what Britannica Editor said: It's used 3 ways,

 
"existential threat
existential questions
existential crisis

The first phrase, existential threat, is used in texts or discussions about politics, usually politics in the Middle East. In this context, existential is being used literally. An existential threat is a threat to a people’s existence or survival.

The second phrase, existential questions, references Existentialism, a 20th century philosophy concerned with questions about how and whether life has meaning, and why we exist. (For more information, look up Existentialism or the philosopher, Jean-Paul Sartre.)

The third phrase, existential crisis, is also a reference to Existentialism, but it is often used in a humorous or sarcastic way, to suggest that the person or people being described spend too much thinking about themselves and the meaning of their lives.

In sum, existential can be a reference to survival, or to the meaning of our lives, or used to poke fun at others who might take themselves a bit too seriously."

Hmm. I probably still won't use the word. But I will say, it is overused and overrated.

What is an existential threat?

I can't figure out why the left thinks Trump was/is an "existential" threat. What does that even mean? That he might run out on our allies and Americans in the middle east? That he might increase our taxes? That he might hire enough IRS agents to populate a small city? That he might drive the economy into inflation and recession at the same time? That he might lead the charge against freedom of speech? That he might collude with the press? That he might encourage the FBI to attack his political enemies? That he might worsen the relationship with China? That he might destroy the fossil fuel industry condemning us to a return to the pre-industrial age? That he might encourage WWIII?

Who exactly is a threat to the United States? I think he's living in the White House, not in Trump Towers.