Why would a narcissist commit suicide? He has threatened to kill himself so many times, and sometimes I think he is really going to do it!
There could be a few possible reasons. Narcissists can hit very low points with the disorder themselves, but, also, they often have co-occurring disorders and/or addictions that can make them more prone to committing suicide.
Narcissists can also use the threat of suicide as a manipulation tactic. This may be used to pull someone back into a relationship with them, prevent them from leaving, emotionally abuse them, or to get something they want.
Like any abuse, suicide threats can escalate, and sometimes narcissists can accidentally hurt or kill themselves in these attempts to manipulate someone.