Some think we do it for the money---but in reality most of us do litle more than break even on our books.
Some think we do it because we like being the center of attention--and while it's nice to be noticed and to have others notice and enjoy our work, many writers are introverts who would be happy just to write and let someone else do the marketing...and speaking engagements, etc
So, why do we write? Because we have a story that infiltrates our minds and lives, a story that must be told, must be taken from our heads to our pens and keyboards.
Often we write, because we cannot NOT write, we cannot NOT tell the stories that mushroom and grow inside us. We treasure our readers, and their patience with us as we work to help the characters in our minds come to life.
As Somerset Maugham said" We do not write because we want to; we write because we have to."
Keep writing and keep reading!