Narcissists can change if they want to.

I will go against the popular opinion and state that yes, narcissists can change if they want to, or if the stakes are high enough. Very similar to its opposing diagnosis, Borderline Personality Disorder, a person that is diagnosed with Narcissistic Personality Disorder can learn to change, if they choose to. One of the reasons they don’t change is that they end up dating or marrying their opposing personality and it feeds into their disorder.

To change, there must be a strong desire and a goal. For example, there has to be something or someone just quite out of reach and all the manipulation, lying, and persuasion won’t get them the thing they want. Their acting out is met with being ignored, or worse yet a turn-off for the person they are trying to woo.
The NPD client then learns that he or she must change their behavior to get the person or object. Not only is it uncomfortable for them, but they learn it can be done and it is now expected that they behave in this new manner.

So yes, the Narcissistic person can change, if they want to. Read more.