Defining the difference between fiction and nonfiction gets overly reductive fast. The former as entertainment and the latter as information.
Lee Child, author of the Jack Reacher series of novels about a former military policeman who wanders from town to town dispensing rough justice, breaks it down in terms of early human history:
Fiction evolved for a purpose. Warnings and cautionary tales could be sourced from the grim nonfiction world. A sabre-toothed tiger will kill you. O.K., got it. Fiction pushed the pendulum the other way. It inspired, and empowered, and emboldened. It said, No, actually, there was a guy, a friend of a friend, who came face to face with a sabre-toothed tiger, a huge one, and he turned and outran it, all the way back to the cave, safe as can be. So don’t panic. It doesn’t always turn out bad. Then, perhaps a hundred generations later, the story evolved, and the friend of the friend killed the tiger. The action hero was born. Strength and courage would save us. And it worked. Fiction in its various forms proved just as powerful to our survival as any other factor.
So remember that when you’re putting a final polish on your dyslexic detective novel or zombie romance trilogy, you’re not just helping people to kill time, you’re helping out the species.