And they are very bad rules. Even though Il Trumpe styles himself as a brilliant negotiator, he’s actually really bad at it overall. While this list was from a post about trade negotiations in particular, I see no reason why they don’t apply to everything he does (boldface mine):

1) President Trump is the least informed person at any table. Everyone he deals with has a background on the issues and/or reads the briefings. That puts them at a big advantage over Trump. Trade is a good example here. Trump thinks trade is zero-sum. This is the equivalent Trump having three barbie dolls and five barbie outfits, and his opponent having two barbie dolls and five barbie outfits. Since no wealth is created by trade, he wants a deal where he just ends up with more of each thing. This is unrealistic and not useful. But, in reality there are people who have barbie dolls and then there people who have barbie outfits. And, if someone has five barbie dolls and someone else has ten barbie outfits, both sides can gain a lot by trade. The barbie outfits are very valuable to the person with five barbie dolls (and no outfits), and the barbie dolls are very valuable to the person with barbie outfits (and no dolls).

2) President Trump is not patient. Negotiations are hard and take time. Trump does not like either hard work or spending time doing things.

3) President Trump cannot keep quiet. It is psychically impossible for Trump keep his cards to himself. His opponents have asymmetric information: they know everything about him and his position.

4) President Trump does not actually care what happens. Trump actually cares about Trump looking good for a few minutes, more than the long-term impact of anything. In other words: Trump has an incredible discount rate for anything that happens a few days from now, where we should value what happens a few days from now.

5) President Trump is personally corrupt. Trump would certainty take things that benefit himself or family personally, over the good of his country. This is a classic principle-agent problem: he is a bad agent for US.

This is where his narcissism really hurts. He is disabled, and, in politics, people will take advantage of that disability.