Ask many writers this question and you will receive many different answers.
When I started to write it was more of a compulsion rather than any lofty goal or ambition. Writing has been my sanity saver on many occasions. From the tortured teens, to marriage breakup, to bankruptcy and business failing, through domestic violence. Writing has been my mainstay where I work out my problems, get rid of feelings (especially the hurt), and find acceptance and rediscover my sense of self.
Others write because they have a story to tell. Some write because it is a part of their everyday work. I doubt there is one writer who picked up a pen with the intention to become a world renown writer.
Some writers write poetry, some fiction, others memoirs, and yet others non fiction. Be it a brief flash, a moderate discourse or an epic saga, writers write because they love it. They need to write as much as others need to run, or breathe. It is their drug of choice.
I look back at my first efforts, and where once I would have cringed, I now have a sense of pride achievement. I started writing and I finished many pieces, and most of them are of novel length. Yes there are some I never finished, and they are not as many as I feared. Why should I feel a sense of achievement over pieces with sentences of 50 plus words, and paragraphs giving rambling roses a run for their money? Because I developed my own style, voice. I learnt a lot through the effort. I recognised early where my strengths and weaknesses lay. Not everyone writes poetry with their morning coffee, nor a short story before bedtime. I found my niche and wallowed in it.
When I finally joined a writers group, I looked back and saw the change, the growth. Most importantly, I could see the stack of exercise books and say to the others, I have finished x amount of manuscripts.
Some of those early efforts will probably never see the light of day. They are a milestones in my writing journey. Others I will assess their worth and consider fixing them up, bringing them into a better state. Who knows?
Today I am still writing. I had an hiatus for a few years, but writing was still there. I spent 5 years, scouring the internet on writing techniques, attending workshops, educating myself, acquiring knowledge and getting to know myself even deeper. I still attend workshops and conferences, do online courses and scour the internet for articles on writing.
Why do I write? I may as well be dead, if I did not write.
Why do you write?