I came across this story, and thought it was worth linking as a cautionary tale

https://news.sky.com/story/lord-of-the-rings-sequel-must-be-destroyed-after-tolkien-estate-wins-copyright-case-against-writer-13033765

There have been a lot of questions on another site I am on about making money from Fanfiction, and after reading this story – the guy was forced to pay $134,000 in damages and destroy all his work – I think that we have a more or less definitive answer.

And the definitive answer is no – it is not worth trying to make money from fanfiction :)