Writing is therapy, an urge that overtakes, something that must be done, a beautiful madness.
Writers can't help but be writers; lots of people have a go at writing but its the ones who keep going (whether they are published or not) who are actual writers - the ones who must. So many of the writers who inspire me had little or no success in their own life time but were unable to stop: Kafka, Baudelaire, Nietzsche, etc etc.
Writing is first and foremost a private activity - we write for ourselves - we tell ourselves stories; it is after (if at all) that it becomes public.
Why do I write?
Simply because I cannot stop.