Narcissism has been classified as a personality disorder. All that says is that it is out of sync with what is considered to be normal behavior and perspective. But it also suggests that narcissism is a choice. That choice may be based on disturbing childhood experiences, but it is still a choice. I believe that fear is the primary cause of narcissistic behavior, but the fear does not need to be current. In other words, acting in a narcissistic way is how the narcissist learned to deal with fear throughout his life.
It is my opinion that narcissism is a type of addiction. The narcissist has chosen and continues to choose his behavior because he believes it works for him. Over the years he has gained enough from this behavior that he continues to use it even in the face of negative consequences. It is his default conduct and he has learned to apply various techniques in different circumstances. It may be that he has done it so often and has convinced himself so strongly of its value that he simply no longer thinks of it as a choice. In other words, it just comes naturally to him.
A simple observation from the Bible has become a well-known saying in our culture:
“As he thinks in his heart, so is he.” (Proverbs 23:7)
Those in relationship with narcissists are victims or objects, rather than caregivers.