Sense of Entitlement + One-Mindedness + Lack of Emotional Empathy + Lack of a Sense of Proportion = Likely to resort to threats in order to exercise control over the other person.
Here is a more detailed explanation of what I mean:
People with Narcissistic Personality Disorder often get very stuck in the present moment. They decide that they want something from you. In the background is their vast sense of entitlement that is working like an emotional and oversized engine. They literally believe that, of course, you will do whatever they ask of you.
Then comes the shock: You say “no” or you propose something different.
Narcissists suffer from “one-mindedness.” Like a small child, they cannot grasp that different points of view can be equally valid. Therefore, the only way they can interpret your “no” is as a direct attack on them. In their mind, you are saying they are wrong. This makes you their enemy.