Donald Trump worries and even scares me, and he worries and scares me for reasons that have nothing to do with his chances of becoming president, which remain nil.

1.) It's not just that he's a bigoted, sexist, xenophobic bully. That's cause to dislike him, but not to fear him. The problem is that his success has given a lot of other people permission to be bigoted, sexist, xenophobic bullies. He excites dark passions that are muted in civilized societies because those passions make a civilized society difficult to sustain, and that alone makes him dangerous.

You can see that dynamic play out in real time at his rallies. In a speech just before the New Hampshire primary, for example, he reiterated his debate promise to "bring back waterboarding and a helluva lot worse than waterboarding," and he went on to criticize Ted Cruz for daring to object. A woman in the audience then yelled out, equating Cruz with an exceedingly vulgar term for female genitalia.

A decent man deserving of leadership would have ignored the outburst. Trump encouraged it.

"She just said a terrible thing. You know what she said?" Trump told the crowd, clearly pleased. "Shout it out again, because I don't want to say it."

She shouted it out again, as directed.

"OK, you're not allowed to say -- and I never expect to hear that from you again," Trump said, feigning indignation. "She said -- and I never expect to hear that from you again -- she said 'he's a pussy'!"

At any other moment in American history, from any other candidate, such behavior at a public event would disqualify a person from presidential politics. Yet the next day, in a primary for a party that claims to bemoan the coarsening of American culture, Trump drew more than double the votes of his nearest competitor.

2.) I worry because Trump thinks that American voters are -- to use one of his favorite words -- stupid. He does not respect those whom he attempts to lead. He believes that they can be easily manipulated, and so far they're not exactly giving him cause to rethink that belief. From birtherism to abortion to guns, he has shown the con man's instinct of reading his intended victim and repeating exactly what his mark wants to hear. They agree to be fooled, he agrees to fool them.

Take his approach to evangelicals. He has used a cartoonish and transparently insincere mockery of Christian faith to pretend to be one of them, and while it has offended some evangelicals, many others have pretended to buy it. Their eagerness to abandon what they claim to hold most dear in order to join his cause could only confirm Trump's dark and cynical view of his fellow human beings.

3.) I worry about Trump's impact because he is constantly running down America, and because people believe him. His constant refrain is "America doesn't win anymore; we never win," and by almost any metric that you care to use, that's ridiculous. We continue to win in almost every setting, every context.

Our recovery from the Great Recession, for example, is unmatched by almost any other economy, and the countries that Trump claims are eating our lunch -- Mexico, Japan, Russia, China -- face problems much more challenging than our own. The United States of America, by far the most powerful nation on the planet, cannot begin to act like an aggrieved victim on the international stage without profound global consequences for ourselves and everyone else, yet that is exactly how Trump would have us behave.

4.) I fear him because the only solution that Donald Trump offers America is Donald Trump.  Through sheer force of personal will, Trump will build the wall and make Mexico pay for it, Trump will crush ISIS, Trump will end the heroin epidemic, Trump will "be the greatest jobs president that God ever created," Trump will deport 11 million, and of course Trump will "make America great again."

How will he do all that? "How" is not a valid question. The only question is "who?" and it has only one answer.

However, the implicit price of Trump making this country "so big, so strong, so powerful" is to first make Trump "so big, so strong, so powerful." He is selling an approach in which he succeeds by brooking no opposition, foreign or domestic, and he is asking the American people to validate that approach. A depressingly large number of our fellow Americans are willing to do so.

5.) Finally, I fear Trump because of what may come after him. He is telling his supporters that they have been betrayed by the nation's economic and political elite, and they believe him. That sentiment is damaging enough in its own right, but Trump compounds it because in the end, he is capable only of a much deeper betrayal. He cannot achieve any of the things that he claims, and when he fails -- not if, but when -- his followers will take that failure as yet another confirmation of their betrayal by a system in which they already have little or no faith.

I don't know where things would go from there, but I'm not eager to find out.