Ok, if taken as medical term (which happens way too often with these words) it can be seen as derogatory and making fun of a psychological disorder.
But I'd argue that no average person thinks of the word that way. I don't think narcissism is ever seen as disorder in popular culture. From outside perspective it looks more like a choice, especially when compared to autism, schizophrenia or mental deficiency. None of those look like choices (autism being the most debatable out of the examples).
In a colloquial sense narcissist is just a selfish asshole. When talking about horror story narcissist, sociopath and / or psychopath depictions, I'm hard pressed to feel empathy for these characters. I'm not saying they are not sick, but having a disorder doesn't automatically make actions and motivations any more justifiable.