I work as an editor. I often have projects that are self-help/ inspirational books with multiple authors each contributing a chapter. They have short bios at the end of the book for each author and most of them list degrees, either Master's degrees or doctorates. You would think that they would know how to write given those credentials but the amount of editing I've had to do with some of those supposedly highly educated individuals is just mind-boggling. Not even nitpicky mistakes but very basic grammatical errors throughout.