The Little Shaman is a spiritual coach & specialist in cluster B personality disorders, with a popular YouTube show and clients worldwide.
Narcissists are generally not happy people. It would probably be fair to say that most narcissists don't even know what real happiness is. Now of course, there are many people of all types who don't know what true happiness is, but unlike pathologically narcissistic people, they probably at least have the capacity for happiness, even if they've not tapped into it yet. It is questionable whether narcissists even have the capacity for happiness at all. More than likely, many do not.
To the narcissist, "happiness" would probably be described not as the presence of a feeling, but rather as the absence of a feeling. If they are not feeling worthless, then they are feeling happy. If they are not feeling angry, then they are happy. Their understanding of emotion is often very poor, as is their expression of emotion and many times when asked, they cannot describe their feelings beyond basic language: sad, mad, bad. Their interpretation of happiness then could perhaps better be described as "not-mad" or "not-sad" as opposed to being understood as its own separate thing.
Narcissistic people usually have a very low capacity for happiness because they are so overwhelmingly negative. Everything is a hassle and a problem and a bother for them. Everything is a huge issue. It's not just because they are in a bad mood from their own self-abuse and self-hatred, although that's part of it. It's because they won't allow themselves to just be happy. They can't let well enough alone. If something good does happen, they can usually be counted on to ruin it for themselves somehow. Inside, they believe - either consciously or subconsciously - that they don't deserve anything, including to be happy. That's why you see so much self-sabotage and self-defeat with pathologically narcissistic people.
Narcissistic people believe they must be perfect and anything less than that is a total and epic failure. They chase success but don't find it because their standards are unreasonable, and because any result other than perfection is regarded as an indictment of them as a person. They attach these perceived failures to their own self-worth because they have no real way to regulate or balance that, which of course results in disaster. When you are unable to accept yourself, you will not be happy. You will not even be satisfied. The closest they can come is probably need fulfillment. When their needs have been fulfilled, they may be content - for a time. The problem with this is that there is always another need and therefore it cannot last.
Happiness is not something you find. Happiness is something you create by being open to it and breaking negative thinking patterns. True happiness comes from within, from self-love and self-worth. It's safe to say that in that area at least, narcissists are barren and empty.