It's really that simple.
I write because I have stories to tell. If people want to read those stories, if they find value in my stories, if they come to love and appreciate the stories as much as I do -- that's the most flattering, humbling, and best compliment an author (nay, an artist) could ever receive.
And as much as I love and appreciate my readers, the truth is, I'm selfish. Like most writers, I write only for myself. I write the stories I want to read. I tell the stories that amuse me, and only me. I tell the jokes I like to hear and which amuse me, and that you may or may not come to fully appreciate. The bottom line is, I'm not writing for an audience, I'm writing for an audience of one -- me and only me.
Of course, that doesn't mean I ignore my loyal readership's input. I listen. I do. But at the end of the day, I'm writing because it acts as a balm to my soul. It makes me feel good inside just to get the words out and, well, that makes me a selfish writer.
Does that make me a big-shot? I don't think so. I'm giving very little consideration to what others have to say, sure, but it only makes sense. After all, nobody in their right mind would try to tell an artist exactly how they ought to go about painting a portrait when what they are painting is perfectly fine. The artist is fully capable of making their own artistic choices. The art is there for your amusement, but it wasn't intended for you.
What's more, nobody but the critic would ever tell a professional painter how to improve their paintings merely to suit the personal tastes of the critic, when that artist could probably care less about what that critic's tastes are -- because he (the artist) is a grand artificer, he or she paints for art's sake, not the sake of his or her critics.
I suppose the same can be said of most writers too. Most authors in the entire history of the written word have written the stories they have wanted to tell -- and those that didn't -- well, suffice to say they either burnt out only to fade into obscurity or they came back with a vengeance and ended up writing their magus opus.
So I write because I love to tell stories. I write because, for me, writing is like breathing -- I need to do it or I feel I would suffocate until I gasped my last breath and then dissipated into non-existence leaving nothing behind. Writing is how I leave my stamp on the world. It is how I cope with and make sense of the world. Writing is something I need to do just to stay sane.
That's why I write.