There is much written about the narcissist on the internet and, so I believe, much of it is wrong.
There is the opinion that the narcissist needs narcissistic supply. Well, this is quite possibly the fact which is most wrong.
What the narcissist needs most, is support and that is mostly on a material level. So, if you notice that you end up helping a partner constantly and that nothing or little comes back in return, well this is the most important symptom and can be recognized easily as well. If you feel, you are stretching your resources financially and physically, this ought to be the most important alarm sign.
The narcissist, is simply a person who cannot do much for him/herself and expects others to run around for him or her. This fact coincides with the knowledge that narcissists are generally people who have been spoiled as children and expect this pattern to continue. The idea that narcissists are abused children, appears wrong when looked at it from a cognitive point of view. An abused child knows that (s)he cannot demand. It is not even a concept (s)he has been able to form. Only a spoilt child develops the concept that (s)he can demand. An abused child might turn into a fighter or psychopath but not into a narcissist.
Narcissists are only as successful as long as they receive support from a support network. In fact, it is part of the psychological description of a narcissist: Not to be self-sufficient.
Well, as can be imagined, this support network is shrinking in time, and the answer appears to be more and more to find a partner who can be made believe that because of love (s)he has to do everything for the narcissist. (The parents of a narcissist would be just too happy if the narcissist found a new partner because it takes the strain away from the parents the narcissist puts on them). Of course, children are one other support for the narcissist and hence, a narcissist might want to cling on to a child or even a grand child. (This is actually quite an archaic thing, to expect children to help a parent in old age and hence it is deep seated in our psyche.) Narcissists are ruthless when it comes to obtaining resources.
There is this big question: Why is the beginning of narcissistic relationship so grand? This again, is actually - well in hindsight - an easy question. The beginning is just as grand as you make it, because you do most of the running around. The sex life is as good, as you are. The fun is as much fun as you are. The conversations are just as good as you can be. It is all centered around you, and the narcissist just watches and goes along with everything.
This is unfortunately very dangerous. Not only that you burn yourself out, but because you are so much in the center, the narcissist prepares you for the emotional attacks later. This is why you end up doubting yourself, because there seems to have been an element of narcissistic behavior on your side at the beginning. This is of the kind: It was all me, hence it was all for myself. Quite some tricky logic, but it works.
Why is it that you love the narcissist so much? Again, in hindsight, this is an easy question and has some almost sinister answer to it. The narcissist reflects you back to yourself and you actually love this reflection which is your own. So, this brings now the biggest confusion about: In the classical sense, you are actually turning into a narcissist (loving your reflection) but in the psychological sense the other person is the narcissist and you are the victim.
Another twist: Because, the narcissist has been reflecting you back to yourself, you are ready for manipulation. Everything the narcissist says seems to have become your self-reflection and that is when all turns crazy. Who is who - am I me or am I this reflection.
Are there any successful narcissists out there? Well, as mentioned, the narcissist is as successful as the support network. There might be some strange cases where the support system stays with the narcissist, but this must surely be the exception. Hence, it is much more likely, that the narcissist will end up in ruins - emotionally, physically and materially. Step by step, their world falls apart. If the so called Sam Vaknin is a narcissist, then he is only successful because of the network around him. However, it appears to me that he is just a very good business man now and a lame cult leader who keeps regurgitating his own nonsense.
Does the narcissist want you to be weak and destroyed? This is a good question and the answer is not quite that simple: Ideally, you are supposed to run around for the narcissist. You cannot do this, if you are too weak. This is the reason why the narcissist cannot stand it when you are ill. If you are too ill, the narcissist will run away. The narcissist will certainly not help you under such circumstances. The narcissist does not want you to be too strong either, because then you would run away instead of running around the narcissist. So, the narcissist tries to keep the balance. When the narcissist thinks you are too strong, you get bashed, and if the narcissist thinks you are too weak, the narcissist withdraws.
Is there some good advice: Yes: Love yourself and not your reflection.
And: There are a lot of nice people out there. Don't accept just any nasty piece of work because (s)he might be the only one you'll ever find.