Recently, on TheWritersView loop, Frank Ball asked the why question and a number of members responded. Their reasons varied. Some were practical, a few quite spiritual in tone, and I wouldn't argue with any of them.
Here's my response: I write because I'm so full of myself I believe the world is waiting to read my words. I went on to say that it takes a certain amount of conceit to be a writer.
One member objected to the word conceit, but I stick by my statement. I assume she objected to the implication of pride or self-importance, but that's exactly the point I wanted to make. What is more arrogant than to think that I could write words to enrich or change others? Even if my purpose is purely entertainment, doesn't that suggest smugness? Try it another way: Who am I to think that I could entertain or enlighten someone else?
To be a successful writer takes a certain amount of conceit.
It means I believe that I have something significant to say.