Go right ahead with your intervention. Then, run for the hills.
A person with full-blown NPD does not care whether their friends are hurt, concerned, afraid, or any other emotion. Narcissistic personality disorder is a choice of behaviors that inflicts harm upon others for the sole benefit (or, entertainment) of the NPD. An NPD has one friend, only: themselves. Every "good deed" has an ulterior motive with gratification at the core. Personally, I don't have time to fool around with NPD and opt to choose friends who are positive and genuine.
Each and every one of us human beings has the ability and opportunity to behave in a narcissistic manner, but there is quite a difference between NPD and just being an *sshole.