Successful authors do owe their fans a completed series.
At a certain point of success and popularity, as a successful author you do owe your fans your best effort to at least be trying to finish a series.
Obviously George R.R. Martin’s an easy target here, but the guys clearly working on everything but finishing GOT, even if he says he isn’t. His fans have been supporting him for decades now with the hopes of eventually seeing how his story ends, and that hope seems all but foolhardy at this point.
By contrast, Robert Jordan did everything he could to make sure his fans who supported him and made him rich got the ending they deserved by passing the torch when he was no longer able to continue on, something George R.R. Martin has made it clear that he has no intention of doing.
Am I saying I expect him to get a book written by next week or something? No, of course not. But I think he owes his fans to at least sit down and do everything he can to put out a new book, and stop being distracted by a million other things. Having personally recently read 2 series that are almost complete, (Dungeon Crawler Carl and Red Rising) I can’t imagine falling in love with those world and characters and never knowing their intended end.
Edit for clarification: I’m not unsympathetic to how difficult it is to write a book, especially when there are so many expectations for it. As much as I diss George R.R. Martin, I know he’s got his work cut out for him and it’s not as simple as “doing what the show did but better,” my argument is that when your fans make you multi-generationally rich, you owe it to them to give them your best effort.