You want to be a writer but wondering that all good things have already been written. This is not a correction assumption. There is still a huge demand of new writings as well as new writers. Why?
Larry King explains this in his really good book “How to Talk to Anyone, Anytime, Anywhere”:
In Chapter 10 I mentioned Shirley Povich of the Washington Post. He became one of America’s most respected Journalists by following his personal creed: The story has never been written that couldn’t have been written better.
So you could be the next writer to write something in a better way on your subject. Start writing.