If you're a consultant, or want to be, you need to read this blog by my colleague, Tonya Price:
I agree with all of Tonya's 5 points, and I'd like to point out one other way writing a book helps you become a successful consultant. Writing a book is not a one-way street, sending ideas from you to clients and prospects. Writing a book is a way for you to learn new ideas and new ways of expressing your ideas.
In my experience, if I want to learn some new material, the best way to do that is to write a book about it. Even if I never publish the book—even if I never even finish it—and don't achieve Tonya's five benefits, I still benefit by becoming a better consultant.
So, even if you're afraid that you don't write well enough to be a successful author, you ought to start writing a book about something you'd like to better understand. And, a good first step is to take advantage of the Write Stuff 2016 bundle of ebooks.