I'm not a full-criteria narcissist or a borderline. I have traits of both, though. I agree, there are some smart folks here. I also like the politics forum. In my experience when they say narcissists are close-minded they tend to refer to the tendency for many Cluster B personalities to control their immediate surroundings to mirror their own reality.

So for instance, say I am politically a leftist. I will thus actively avoid all conservatives, capitalists and religious people, and try to change the minds of my more agnostic friends to fall in line with my views. I will turn them against their friends who may have opposing views to mine. Through confirmation bias I will end up solidifying my philosophy with books that agree with me. You won't find me reading Friedman or Hayek, for instance. My Kindle will be full of Marx and other leftist ideologues. If I meet someone and hang out, I will drop them from my life the moment they let even the slightest hint that they don't believe in the redistribution of wealth. If anyone questions my ideas, I will first dismiss them as idiots, but if they press hard, I'll get personal with them. Others exist to validate my world, my thoughts, and my way of living. I want you to reflect me, to agree with me, and to make me feel right and smart. If the world invalidates my beliefs, the world is wrong.

I won't be able to agree to disagree, but still appreciate the parts of the person that aren't at odds with my political leaning. I must eject them from my life, because their very existence threatens my understanding of the world and myself.

Funny thing is I actually know quite a few people like that. I would say it's a narcissistic trait but also a trait of other personalities. But not all narcissists are alike, and it's also a matter of degree. One may show his or her narcissism in intellectual matters, another in sexual matters.

The idea behind the above is to maintain a sort of homeostasis where the individual's personality and worldview remain static, because that validates their own existential experience as well as provides them shelter in a psychological comfort zone. So in the above case, leftism hypothetically validates my experience because I may have had problems with money and have grown up poor and thus felt a disdain for those who benefit in a capitalistic society. I knew someone who was like this with racial matters. When one engages in this kind of social fortress-building it's almost always personal and existential. The ideology or faith they ascribe to validates their own personal experience from birth to the present.

What all these things like confirmation bias and the process I discussed above do is create more or less a safe haven for a person via a network of enablers, sycophants, and people who think and feel the same way. Thus there is no opportunity to be challenged and develop humility, curiosity, or come to admit one's faults. There's also no incentive to change, grow, or learn anything. Mental maturation remains confined, and the person finds it difficult to integrate feedback from others and from the world around them into his or her worldview. As we grow we integrate lessons learned from new experiences and from new associations, and this helps us grow, mature, and gain wisdom. We often disagree with friends and colleagues about, say, politics, but enjoy them for their unique personalities, their upsides, and maybe the things that we do both agree on, and this helps us grow social intelligence and empathy. The person who engages in what I've described before is in fact closing themselves off from this process. They may be able to tell you everything you need to know about Marxism and put it in a perfectly eloquent and vibrant package, but they wouldn't be able to offer anything other than that which validates themselves.