Finchbearer
Istar
That is motivation to not write fanfic.Money and feeling of ownership are 2 very strong motivators. Say you write fan-fic in the universe of an author. You write a lovely fan-fic novel, which takes 2 years to complete, and you put your heart and soul into it. The story is liked by the fan community of said universe. Now that universe blows up and becomes the next Marvel. The next movie comes out, and the story is the exact same one you wrote. The author earns $100 million.
How do you now feel? Most people would feel ripped off and cheated and like they are entitled to at least some of that $100 million. Even just 1% of that kind of money is life changing. Now imagine if you know that the author has read your story before work on said movie started?
And it can happen on a smaller scale as well, simply because most people have no idea how little an author actually earns. I mean, they see someone wrote a bestseller. That can simply mean you sold 10k copies which made you $2 each. Hardly stellar. But they don't know that. They only see bestseller and assume you're making millions. And they want some of that.