(CNN) In five days' time, President Donald Trump will travel to Singapore to participate in history: He will become the first American president to meet with a sitting North Korean leader .

Trump's summit with Kim Jong Un is a massive moment -- not just in Trump's presidency but in the course of diplomacy for potentially decades to come. North Korea has been a rogue and aggressive presence on the Korean peninsula for decades, but its acquisition of nuclear weapons makes it a worldwide problem.

How is Trump preparing for this huge sit-down? He isn't.

"I think I'm very well-prepared," Trump told reporters during a photo op with Japanese Prime Minister Shinzo Abe on Thursday. "I don't think I have to prepare very much. It's about attitude."

It's about attitude. If you were looking for a perfect three-word summary of Trump's political life -- or, actually, just his plain old life -- that's about as close as you could come to nailing it.

Whether it's making a real estate deal, starring in a reality TV show, kicking off his presidential bid or actually being President, Trump's basic view is: "I've got this."

Trump has turned his belief in himself -- whether or not facts support that confidence -- into a life mantra.

"Develop your gut instincts and act on them," he tweeted in 2013 . "You will have your biggest successes when you go with your gut--but be very smart & careful."

In 2014, h e sounded a similar note : "Trust your instincts. They are there for a reason. Without instincts, you'll have a hard time getting to--and staying at--the top."

His 2016 presidential campaign was Trump's ultimate experiment in faking it until you make it. He eschewed policy briefings or any sort of traditional debate prep. As a result, there were moments during the campaign when it was clear that Trump had zero idea what he was talking about.

The most famous/infamous example of that came during a debate in the Republican presidential primary season when conservative talk show host Hugh Hewitt asked Trump what his priority was "among our nuclear triad?"

"Well, first of all, I think we need somebody absolutely that we can trust, who is totally responsible; who really knows what he or she is doing. That is so powerful and so important. And one of the things that I'm frankly most proud of is that in 2003, 2004, I was totally against going into Iraq because you're going to destabilize the Middle East. I called it. I called it very strongly. And it was very important.

"But we have to be extremely vigilant and extremely careful when it comes to nuclear. Nuclear changes the whole ball game. Frankly, I would have said get out of Syria; get out — if we didn't have the power of weaponry today. The power is so massive that we can't just leave areas that 50 years ago or 75 years ago we wouldn't care. It was hand-to-hand combat.

"The biggest problem this world has today is not President Obama with global warming, which is inconceivable, this is what he's saying. The biggest problem we have is nuclear — nuclear proliferation and having some maniac, having some madman go out and get a nuclear weapon. That's in my opinion, that is the single biggest problem that our country faces right now."

Here's the shorter version of Trump's answer: I have absolutely no idea what the nuclear triad is. Or was.

But, wait, there's more! Hewitt followed yup by asking his same question again: "Of the three legs of the triad, though, do you have a priority?"

Here's how Trump responded: "I think — I think, for me, nuclear is just the power, the devastation is very important to me."

Um, what? The nuclear triad covers the three ways that the United States can launch nuclear weapons . What Hewitt was asking was whether Trump had a preference between land-based delivery, sea-based or air-based. Trump said he liked nuclear power. That's like someone asking what specific event you like the most in the Olympics and you responding: "Olympics."

Despite incidents like that one, voters didn't care -- or didn't care enough not to vote for him. (Less than four in 10 voters said they thought Trump was "qualified" to be president, according to 2016 exit polls .)

And, the lesson Trump took from his stunning victory was this: His gut was right, Everyone else -- including the political establishment of both parties -- was wrong. The 2016 election became the strongest proof point for Trump that he knew everything he needed to know about, well, everything. All of the so-called smart people in Washington who had studied campaign and politics for decades didn't understand people -- and what makes them tick -- like he did.

In fact, Trump -- during the 2016 campaign but especially after it -- seemed to revel in the fact that he wasn't some egghead, studying up on every issue. Trump cast those types as part of the problem -- out-of-touch elites who spent all their time reading books and no time at all dealing with actual people.

Book smart was out. Street smart was in.

Which brings me to Trump's belief -- as expressed on Thursday -- that the key to the summit with Kim isn't policy, it's attitude. Be tough. Be willing to walk away. Let the other side know you are serious. Details are for staff to work out, not for the big boss to worry about.

It's a view on life that has gotten Trump to this point -- so dismissing the "attitude" approach out of hand is a mistake. But international diplomacy -- with nuclear weapons in the mix -- seems to be something different altogether.