I’ve seen people talk about actors and artists that had a terrible time.
My own would be Anne Rice. She wrote Interview with the Vampire after her young daughter died of Leukemia. Then her husband suddenly died of a brain hemorrhage. I suspect her Christian, anti-fanfic phase was a result of mental illness and manipulation from the publishers, although I don’t think she ever apologized.
Timothy Zahn (and many of the Expanded Universe star wars novelists like Karen Traviss, Matt Stover and Aaron Allston). Their work, and Zahn specifically made massive contributions to how we think about star wars and the fandom. Instead Lucas disparaged them and Disney hacked out a few of the good bits like Thrawn and put them in the hands of vastly inferior writers.
The whole point of doing tie-ins (aside from the check) is that it attracts readers to your original work but I doubt that was true for many, and that’s a shame.
The only sequels we all ever wanted were the Thrawn Trilogy.