the predisposition required for a cure would automatically bring it about. most say no. by the time a narcissist is fully developed, that IS their reality and they cannot help but see all of existence in that context. it is self fulfilling and self supporting. it is literally an existential black hole into which anyone else who cares about the person enough to get close will get sucked in. they are very painful people to know for you must care about them from afar and never be able to get close enough to effect change for the better.
most narcissists are intelligent and functional. they can never be convinced they have a problem or need to change - it is always the other person that the problem, be it jealousy or stupidity or some other trait inferior to the narcissist.