When writing non-fiction, it's easy to explain your motives. You have a goal. You want to educate. You hope to prove something.
Fiction... Sometimes it can feel like a waste of time. You're making up stories. Who cares?
The simplest answers may be that writing fiction addresses the human condition or comments on a moment in time in our society. Both are important.
But why bother? To a certain extent there is the ego factor. I did this. I like this. I want to share. I seek feedback.
Seeking publication is hard and serious work. Is it worth it? If you don't know if you'll reach the end goal of publication, why bother?
The answers vary.
It can be therapeutic to transfer energy and emotion into ideas on paper.
It can provide a sense of accomplishment.
I have trouble finding enough books I want to read or stories that hit all the criteria that make me enjoy reading.
So, I write them.