I ask, because for me, art, as ambiguous of a term as that is, has been a means to give me meaning in the moment. It later acts as a memento of those moments. A sort of nostalgic trigger.
The act of creating something is sort of a release, and in some way I agree with the OP that it is narcissistic, but there is little we do which isn't centered on ourselves. Where I differ is the negative connotation.
Art as expression is a way for me to "get something off my chest", so to speak. That other people might enjoy it is only a byproduct, and I think many artists feel the same. It's probably the reason so many are discovered only after their death.