We've all known of people who have written one wildly successful book and never wrote again. To Kill a Mockingbird is one example.
My response is, "So what? What's wrong with having one great success? Isn't it better to have one big success than ten failures?" Even though I speak those words, they rarely impact the ones who’ve given into a fear of being successful. Until they figure out how to get beyond that barricade of resistance, they probably won't write.
Fear of failure; fear of success.
Either can paralyze gifted writers.