Occasionally I've been asked who I might like to collaborate with to write a book. My answer is more or less "That will happen over my dead body!" It's my book. MINE!!!
Yet though writing is justly known as a solitary pursuit, that doesn't mean that writers don't like talking with other writers, and that we can find ways of benefiting from such interactions.
I'm part of an online book club of long time authors. We all started in romance, and some have gone in different directions such as mystery, women's fiction, and paranormal. But we're all storytellers in our DNA, and our last book discussion slid into talking about writer's processes (often very different} and that morphed into a discussion of working with others in a constructive way.
Imposter's Syndrome is pretty common, even among successful writers who have written dozens of books. The feeling, usually when one is in the middle of writing a new book, that someone will say "You're a fraud! You don't really know how to write!" This can happen despite the evidence of multiple awards and bestselling books, proving that authors are masters of cognitive dissonance. <G>
As Maris Soule said, "I know I was relieved, years ago, when I heard other successful writers say they feared one day the world would discover they really didn't know how to write or create a story."