I visited Quora tonight to answer this question. I think my answer will surprise the readers and should generate plenty of comments in the next 24 hours. Especially since 99.9% will disagree with me.
Here it is!
Now I have an entirely different response to this question. The premise of the question is debatable according to the agreements I signed with Amazon and JET author Russell Blake.
In 2015 Amazon Kindle Worlds went into contract with RB of the USA Today Best Selling series JET, to produce and pay the original author a portion of the proceeds for fan fiction. I was one of the first authors invited to write into his world. He and I were both paid for every novella that was sold in his “JET World.” It turned out to be a great opportunity for me. I piggy-backed off his exciting character and created my own world around his main heroine.
This year KW was dissolved. We have no idea why. All rights to my characters and stories were mine to keep. At first, I panicked, but I was ready to take my ‘world’ out of the closet and create my own lead character who has blended perfectly with my series. Code Raven, the prequel debuted less than two weeks ago and is already in the top 100 of Amazon shorts alongside James Rollins, Lee Childs, Tami Hoag, and Stephen King!
So this success, although not yet in the same class as E L James, is on its way thanks to the foresight of Amazon to jump on the fanfic bandwagon and pay both the author and the fan/writer.