We're born selfish, in large part because we're also born helpless. An infant knows only that it wants things and that, if it cries out, it will get the attention it needs. At some point, parents begin to teach it empathy and sympathy, helping to form the basis of a basic moral and ethical foundation. Even those feelings are based, to some degree, on self-interest. We're not perfect, but we do what we can to survive and thrive.
I think that narcissists have that developmental stage derailed or improperly managed, so they do not develop a proper emphatic/sympathetic approach to socializing. They do not recognize that everyone else also has some level of self-interest; they see only their own needs and wants, and everyone else is there to satisfy them, just as they were when that individual was a helpless infant. As they become older and more knowledgeable, their methods of manipulation become more sophisticated. Few people will treat grown-ups like helpless babies, after all.
I wouldn't say that it's impossible to overcome, but the type of life-changing epiphany that is required is not something that can be easily produced, nor does it come along very often in our lives (and for some people, it never happens at all). It's something of a curse, in that it can get you ahead for a short time with the people you meet, but over time they recognize that the relationship is very one-sided and they come to resent it. The narcissist leaves a trail of people who are bitter and angry at them, and they are unable to understand why.