One test for confidence vs. narcissism is not as much how self is understood, but how self compares to others. There are people who think themselves absolutely marvelous, but they think everyone else is too. I think this might be called charisma. If there is a strongly asymmetrical view that places self as inflated over others, then that is more narcissism.
Narcissism is also an attachment disorder from the little I understand of it. I believe it can result from problems in the process of the self awareness that occurs in the early stages of infancy through childhood. People begin with only an awareness of self and gradually learn the concept of "other" and how that relates to self. Those early relationships help to establish that understanding. I believe the true narcissist has an undeveloped sense of "other". I should go look up the actual texts on this again.
The first man to raise a fist is the man who's run out of ideas. H.G. WELLS
The first principle is that you must not fool yourself, and you are the easiest person to fool. FEYNMAN If this is monkey pee, you're on your own.SCULLY
Well, I guess I've made a mistake in assuming this is common for ENTPs...but I wasn't really taking it literally. It's kind of an exaggeration of certain ENTP attention whoring tendencies. (The consensus here seems to be that ENxPs have more of a tendency to be attention whores than other types, apparently.)
I don't actually mean to say that most ENTPs lack any real confidence in anything, but with their ability to invent justifications for nearly anything they want to, narcissism seems more likely to occur in extreme examples of ENTP than in other types.
Not saying that most ENTPs are narcissists, but I'd bet that a disproportionate number of narcissists are ENxPs.
If you could be anything you want, I bet you'd be disappointed--am I right?
For me the difference between having the qualities listed in the OP and a narcissist comes with their willingness to exploit and use others to reach their goals along with their exaggerated self importance and sense of entitlement.