In an interview on This is Audible, Campbell Scott mentioned recently that the masterful filmmaker Akira Kurosawa at 80 said something like, and I'm paraphrasing, "I almost have this filmmaking thing figured out."
I find comfort in remarks like that from the acknowledged great.
I struggle with self-doubt like I guess everyone who writes and who has moved past the arrogance of youth. A writer friend of mine, who I've always felt is far more talented than I am, mentioned recently that he'd been plagued by negative feelings.
I guess it's part of the creative process and perhaps valuable if it makes us endeavor to do better.