I really believe that Ns are able to convince themselves that their delusions of grandeur are real. One of the traits of an N is that they expect to be treated as if their delusions/dreams have materialized. I think that may be largely because in their mind, it IS real. To other family members, especially their victims, the N is clearly delusional, but the N sees things much differently.
In my SIL's case, her delusion is a pretty dangerous one. She believes that she's a wildlife handler. I do feel that her getting harmed by one of these animals is inevitable. And when it happens, I won't shed a tear. Normally, I wouldn't wish harm on anyone, but in her case, as wicked as she is, what can I say? Karma is a b!tch.