Here’s a SomeEcard that states the point very well:
I don’t need to hire an editor. My book is perfect just the way it is. – Said no bestselling author. Ever.
1001 Ways to Market Your Books
“If you want to sell 250,000,000 books like we have, read and use this book.” – Mark Victor Hanson and Jack Canfield, bestselling authors of the Chicken Soup for the Soul series
“John Kremer’s 1001 Ways to Market Your Books was instrumental to our success in making The 7 Habits of Highly Effective People one of the two most influential business books of the 20th century.” — Stephen M. R. Covey and Greg Link, authors of Smart Trust