This isn’t quite true. In fact, covert narcissists usually have an incredibly high degree of empathy much higher than most people. This is necessary to remain secret. The difference is that where as most people will empathize and then internalize the empathy resulting in actions and outcomes that are better for the other person, covert narcissists will internalize and discard these feelings as external and irrelevant. While not necessarily sadistic (sadism is basically empathy turned upside down, taking pleasure in the empathic misery of others) covert narcissists will perceive and empathize but remain indifferent neither takin pleasure or feeling pain in the misery of others. Because it doesn’t matter.