In both cases, a narcissist experiences an almost total loss of supply and to avoid the ensuing depression, they lash out and attack others like angry dogs. That’s why old narcissists are so often cranky and mean. They’re also terrified of death, the last thing on the list that terrifies them.
Every narcissist I’ve ever known lives in mortal terror of death. That’s because death is the ultimate loss of narcissistic supply. Death means complete annihilation of the ego and there’s nothing more horrifying to a narcissist than that because their ego is all they are. Personally, I think some also fear hell. They know on some deep level how badly they’ve treated and exploited others and think they might be held accountable for it in the afterlife. I’ve seen a lot of narcissists who suddenly become extremely religious in their old age. I think that’s because they think by being religious, they may be able to ward off any accountability after they die.