I kind of disagree, but it's kind of a 'which is first, the chicken or the egg' argument. I think the lack of empathy is an illusion, kind of like a bi-product of their deep seeded self-hate and yearning to be loved. I think assuming that they don't feel is anything for others is the most dangerous misconception.
Although narcissist's act cruel and vicious at times, they're just like everyone else in that they want to be loved, however, they can never really feel loved because they hate themselves. Nothing anyone does will ever be enough for them so being in a relationship with a narcissist is like taking one "prove you love me" test after another.
Personally, I think narcissism is one of the worst things a person can be affected with. It really does hurt a lot of people including the narcissist.