Empathy implies identity or equality, both abhorrent to the Narcissist. And being perceived by the Narcissist to be so inferior, people are reduced to cartoonish, two-dimensional representations of functions. They become instrumental or useful or functional or entertaining - rather than loving or emotionally interactive. It leads to ruthlessness and exploitativeness. Narcissists are not evil - actually, the Narcissist considers himself to be a good person.
Many narcissists help people, professionally, or voluntarily.
But Narcissists are indifferent. They couldn't care less. They help people because it is a way to secure attention, gratitude, adulation and admiration. And because it is the fastest and surest way to get rid of them and their incessant nagging. It is like watching a movie about yourself.