Donald Trump knows more about everything than everyone, as he'll be happy to tell you. Whether it's taxes, ISIS, hacking, or even scripture ("Nobody reads the Bible more than me," he once claimed), he's always more knowledgeable than the so-called "experts" with their useless training and experience. Whatever bunch of poindexters is trying to tell Trump something, he'll be sure to inform them that they don't know what they're talking about, unlike him.

But nobody likes being told they're stupid and uninformed, particularly when their job is precisely to figure stuff out. And before he has even taken office, Trump is in open war with the intelligence agencies whose job it is to give the president the information he needs to make critical, often life-and-death decisions in foreign policy. How is that going to affect their relationship when Trump is president, and actual lives are at stake?

The reason Trump is angry is that those intelligence agencies determined that Russia was responsible for hacking into the email systems of the Democratic Party and John Podesta, who chaired Hillary Clinton's campaign, and they further determined that the hacking was for the purpose of helping Trump get elected.

You can see why this would displease Trump; he's fantastically insecure about the fact that he won fewer votes than Clinton, which is why even two months after the election he keeps talking about his supposed "landslide" Electoral College victory (not true) and how he would have won by huge margins in the popular vote if it determined the winner. But instead of saying, "These are serious matters and I intend to work hard to beef up our cyber defenses," like any sane president-elect would, he has instead lashed out at the intelligence agencies, regularly belittling them and calling their conclusions into question. One sample tweet: "The 'Intelligence' briefing on so-called 'Russian hacking' was delayed until Friday, perhaps more time needed to build a case. Very strange!" It wasn't actually delayed (he was always scheduled to get this briefing on Friday), but more importantly, nothing says to intelligence officials "I value your work and expertise" like putting the word "intelligence" in sarcastic scare quotes.

Let's not forget that this isn't the first conflict between Trump and the intelligence agencies over this very issue. When the campaign was underway and Trump got his first intelligence briefing, he subsequently went to the press and claimed that the briefers had criticized Obama's policy decision, reportedly angering the officials, both because they don't give policy advice and because Trump violated the terms of the briefings, under which the candidate is not supposed to discuss publicly what goes on there.

Now let's add in the fact that Trump's people have leaked to the press that they plan "to restructure the Central Intelligence Agency, cutting back on staffing at its Virginia headquarters and pushing more people out into field posts around the world." The Directorate of National Intelligence would also be a target, supposedly because it has become too "politicized."

On this we can see the fingerprints of Michael Flynn, who is to become Trump's national security adviser. Flynn was fired as head of the Defense Intelligence Agency, where he was reportedly guilty of gross mismanagement, not to mention the fact that he became consumed with conspiracy theories and feuded with his colleagues, including his boss, Director of National Intelligence James Clapper. Flynn now has his chance for revenge.

On Thursday, Clapper appeared before the Senate Armed Services Committee to talk about the Russian hacking, and reiterated everything intelligence officials have been saying all along about Russian hacking — and which Trump has dismissed out of hand. Asked if the fact that the president-elect is insulting the people who will be charged with giving him critical information was affecting morale, he replied, "I hardly think it helps." He also said that "I've received many expressions of concern from foreign counterparts about, you know, the disparagement of the U.S. intelligence community, or I should say what has been interpreted as disparagement of the intelligence community."

There's no mystery about why Trump is doing this: Like everything else with him, it's personal. The intelligence community said something he didn't like, so he had to strike back at them, because that's who he is and what he does. But consider what happens when there's a foreign crisis Trump has to confront — which there will be, probably early on in his term.

At that moment, intelligence officials will come to Trump with information he needs to know in order to make decisions on which lives depend. They will walk into the room knowing that he thinks they're stupid and they have nothing of value to offer him. If they maintain their professionalism, that won't change what they tell him. But this feud (plus whatever Flynn has whispered in his ear) will have convinced him that they're his enemies. He'll probably start with the assumption that whatever they say is either biased or just wrong. He'll have convinced himself that he knows more than they do. And he'll do whatever his gut tells him.

What if they tell him that some action he's contemplating could produce disastrous consequences? Will he just decide they must be wrong and go ahead with it?

It's important to remember that American intelligence has been wrong at times in the past, and might be again in the future (though we should note that in the most commonly cited case, the war in Iraq, the problem was much less what the intelligence actually said than the enormous pressure put on the intel community by President Bush and Vice President Cheney to produce the "right" answer on Iraq's phantom WMDs). What that means is that the president needs a healthy skepticism about what they're telling him. He needs to be able to test the strength of their evidence, determine how certain their conclusions are or ought to be, and balance what they tell him against other factors weighing on his decision.

Right now, Trump is showing that he isn't approaching them with skepticism, but with contempt. Unless they tell him what he wants to hear, he'll discount them completely. And when it really matters, that could be disastrous.