Should You Tell a Narcissist They Are a Narcissist?
The reason people want to tell someone they think the person is a narcissist is usually a good one. Just like any other problem, if you can see it and others can't, you'd want to tell them about it so they can address it. If someone shoe is untied, you tell them so that they can tie it and then they won't trip. If someone leaves their purse on top of their car and is starting to drive off, you'd let them know so they don't lose all their valuables driving down the road. If someone has symptoms of an illness and you knew someone who became very ill or died that had those same symptoms, you'd say, "Hey, you might want to go get that looked at because my uncle had that and it turned out to be such and such of a thing."
It's the same concept with pathological narcissism. People can see the problem and want to help. But what if every time you saw someone, their shoes were untied and when you pointed it out, they said, "No, they aren't. Your shoes are untied!" You look down. Your shoes are tied. Theirs are not. You point this out but they just keep insisting that their shoes are right and yours are wrong. They never look down and they never see it. When they trip on their shoelaces, they insist that you pushed them. You tell them again that their shoes are untied and they just keep insisting that you pushed them and that you're lying. In a moment of self-hatred, they admit their shoes are untied and accuse you of thinking they are lowlife scum who should just die because yours are tied and theirs aren't.
This is what happens with narcissism. Your intentions are good, but unfortunately they don't believe that and even realizing they have this problem wouldn't change that. It seems real to them in the moment and they will believe their feelings over other people every time, regardless of how far-fetched or even delusional these feelings may seem to be. Feelings control the narcissist and they believe feelings are facts. That's part of the problem.
So should you tell someone that you think they're a narcissist? To be honest, it's probably not a very good idea. Narcissists are high conflict personalities. They are hostile, aggressive, insecure and steeped in pathological denial. In your mind you are attempting to help them. In their mind, you've accused and slandered them. You are blaming them and exposing the fact that they are not perfect. The narcissist's response to this is not going to be one that is conducive to help or healing. They will likely become enraged. Alternately, they could be deeply hurt or simply use it as something new to accuse you of. They're not the narcissist. You are.
Even if none of these things happen, it probably still isn't going to change anything. Narcissist that know they are narcissists are still narcissists. The information doesn't change anything in this regard because, to put it simply, there is a disconnect between their emotions and their intellect. Even if they did understand emotionally what being a narcissist means, it would require an enormous effort to change their behavior, and they would have to first admit they were in the wrong and then rely on other people to tell them when the behavior they are displaying is delusional, wrong or inappropriate - at least at first. Most pathologically narcissistic people are not really capable of trusting someone that much. Most people in general don't trust anybody so much that they would listen to that person over their own feelings or perceptions. It's just unlikely even in the best of circumstances.
Now, that being said, narcissism is a spectrum and many people are not pathologically narcissistic. These types of people may be capable of seeing the behavior themselves if it's pointed out. They also may be capable of addressing. The degree to which narcissistic behavior can be changed depends on the degree of flexibility the person's narcissistic traits possess. The worse the traits are, the more inflexible they are. People with narcissistic traits that are inflexible are virtually not capable of adjusting to new conditions or situations and find it very difficult or even impossible to change things.
Only you can decide if it's worth the risk of telling someone in your life you feel they are a narcissist. If you gamble and lose, you will likely be punished for your audacity for quite sometime. You may even find yourself being accused of narcissism continually. If you truly believe that your loved one is not pathologically narcissistic, you may choose to risk it.
In the end, it doesn't really matter whether the narcissist knows they are narcissistic or not. You know it, and even if they can't change their situation, you can change yours. It is not your responsibility to help someone who does not want to be helped. It's not even possible, and many people go through years of abuse before they realize they aren't actually helping at all. All they're really doing is enabling an abuser who uses their tacit agreement to abuse them more. Love yourself more than that. Love them more than that. Don't enable someone you care about to do things that aren't right. Even though it's hard, sometimes the best thing you can do for other people is nothing at all.
NOTE: Remember that "narcissist" is not a diagnosis. It's a type of person. Narcissistic Personality Disorder is a diagnosis. Borderline Personality Disorder is a diagnosis. "Narcissist" is a general term to describe people who behave a certain way or possess certain traits, people who may or may not have a psychiatric disorder.