There a couple of reasons why someone should be writing. One is for school. Another is for fun, or to remember things that have happened. The final reason is because you have a story to tell. Notice, I never said “because you think the world wants someone to write this specific story.” Never write to everyone. It is like trying to please everyone, or be everyone’s friend. You simply can’t do it. Establish your own writer’s identity and your own fan base. The great ( or maybe not so great) thing about people is they all have different opinions on everything. There will absolutely be people out there who like the stories you’re spinning, the characters you’re developing, and the worlds you’re building. The most important thing for beginning writers is write what you want.
Now about writing to an already established fan base. Whether you’re writing a series or just a stand alone novel,I’m hesitant to go either way. On the one hand, keeping fans who have supported you happy is important. On the other, finishing the story is also pretty important. After all, that’s the whole reason why you started writing. One of hte best examples that I can think of is the differences between the book series A Song of Ice and Fire and the television series Game of Thrones. One of the reasons I love that series is that George R.R. Martin is unpredictable as a writer. Beloved characters get killed off, and there is in no way fan service. The show’s writers, David Benioff and D.B. Weiss have had to be the same way, up until the later seasons. Without spoiling anything (I hope), I think that Benioff and Weiss have definitely paid fan service to Arya, allowing her to live when I think that Martin would have either killed her off or never put her in that situation. It will be interesting to see what exactly happens when Martin gets around to finishing his next book.
But I was really angry at the situation. After killing off so many “main characters,” they let Arya live simply because (in my mind) fans really enjoy her character. For that reason, I would say continue to write your own story, and don’t worry about the fans. They might be upset when you kill off a favorite character, or when the bad side wins, or whatever situation that doesn’t follow popular support, but I think that they will appreciate the story more. Not only that, but you will like the story more, because it is entirely your own. So as I’ve said before, write what you know, and how you want it to go.