You write because there are words in you that want to come out. Come out and play? Come out and fuck shit up? Come out and sit blankly on a page that no one reads.
You write because you can and you must.
You write so that a part of you is left for eternity to review, or for what passes as eternity and what might happen if you wrote and wrote all online and there was an apocalypse and the lights went out for good. All that writing is just gone. In stasis.
If you write and no one reads it, is it real? Does it count?