I think first and foremost- Trump was and is a narcissist, a showman, and a businessman (however good a businessman he might or might not be). It's all circuses, wheeling and dealing to him- play hardball (or even a fair bit deranged) with China and Iran, make a big show of talks with DPRK ("peace with the unimaginable"), he may be of the same hegemonic mentality than his peers, and he might be the farthest thing mentally from a peacenik- but when it comes down to things I think he was someone who could be dealt with, someone for whom the constraints of reality and the circumstances all around him in his country (those who were white, anyways) actually holds some weight. (the same I would not say of mainstream western politics nowadays)

Trump’s a pretty dumb guy, he hears about a powerful man in charge of an entire country that has nukes and Libs hate him, so he was like “Ahhh, he must be a guy like me, I hear he has the biggest army, everyone’s telling me , Mr. Trump please don’t talk to him he’s so scary, and I said lemme talk to this guy. And I said he’s probably a great guy. Not many people know that, he’s actually very smart like me”

I always interpreted it as Trump seeing it as him getting to say he made peace in the Korean peninsula or something.

He tried to make them give up the nukes, as would Al Capone say, "with a kind word and a gun", instead of the usual for US just gun.