I think it depends on a person's purpose for writing.
Some people, at least at the beginning end, write because they really really want to make anime or a video game or a movie including fiction and non-fiction, but those things require resources beyond their reach, such as the cooperation of other people for one. But writing is done by one person with a keyboard or a pen.
I think some of these will decide they love writing for its own sake after a while. And when you reach a point where you're somewhere near the pro level or at least a high-end amateur, you probably have developed a love for the writing itself.