My wife's sister is. And I/we do feel very sorry. What we have run up against for 30 years is that she not only refuses to deal with it in *any* sort of constructive manner; worse, she uses it as an excuse for everything. Nothing is ever her responsibility, everyone in the family is here for her benefit.
It is very frustrating when, on one hand, she admits she has problems (but refuses to call it bi-polar) and then will list all of the reasons she can't do anything about it. No matter what any of us suggest, she always tells us she can't do it.
I think her mental problems are much broader than the bi-polar thing. Of course, no emotional or mental problem exists in a vacuum.
You are probably right that she has broader problems. And, narcissistic behavior is normal for them. They know they are screwed up, and are frustrated that "no one understands". To an extent, she is correct, but most of us in the business do understand that they have little control over their behavior. Behavior is a symptom of their illness, as is the way they think. Now, if only we could find out how to fix that...