Why would a narcissist take their own life if they think so much of themselves?
The thing that a narcissist hates the most is feeling vulnerable and exposed. Not exposed as in reveal their mask and all that BS that you hear about all time, it's not that. It's exposed as in they are capable of being harmed because there's nothing to protect them.
The reason why narcissists desire control so much is a defensive thing. If they completely control their environment, then they control all the risks. If the control all the risks then there's no chance of being harmed in a way that will potentially send them into depression.
When a narcissist feels like somebody has taken something from them, they feel like a victim. So, if you had got the upper hand in some way or they blame you for something in some way that caused them a loss, whether it's real or perceived it will make them feel like a victim.
Feeling like a victim brings back all the feelings from childhood that they deplore. Everything that they're trying to avoid is due to feeling that way. Feeling invisible, feeling like a failure, like you're not good enough, like you'll never be good enough, and you've got no future. This is their core shame. This is the thing that they try to avoid at all costs.
When they can't, they're unable to regulate their emotions. This is the narcissistic collapse. It's an endless spiral downwards into depression that gets so low that they can potentially go and commit suicide. The thing about narcissists and suicide is that they are the highest risk population for committing suicide due to depression. They plan out their suicides to the letter. It's meticulously a thought out and that is something that you do when you're in the darkest of depressions.
Feeling like a victim is not an option for them. That is why all their defenses around that are to ensure that they don't start to feel like a complete failure and like they have no future because that depression is a very real suicide risk.
They may act like they are invulnerable, but that is the only way that they can stay ahead of that inner shame. It's the only way that they can keep in front of that feeling of being worthless, that feeling of being garbage. Anger is a protective emotion. That's why it's their go-to emotion.
They're invulnerable as long as they're in rage. That is why when they need to bolster themselves, they will get angry at you and make it your fault. It offloads the shame onto you and they deal with it through anger. This is the crux of why the relationships can get so destructive.
That is the core root of their biggest fear— that they are worthless. That is their core pain.