Writing is both an art and a craft. The art is in the story you tell, and the craft is in the way you tell it. Learning to separate these two things can help you understand and accept any criticism you receive from an editor, whose ultimate goal is to improve the overall quality of your work.
Some authors are too close to their work to accept any kind of criticism. They take it far too personally, and suggesting ways to improve their writing is seen as an insult.
The best authors are able to separate their work from themselves. They see the value that a good editor can bring. They are able to acknowledge weaknesses in their writing and turn those weaknesses into strengths prior to publication.
Putting together a book can require enormous amounts of time and energy from a variety of people, as can be seen by reading the acknowledgments section of any traditionally published work. As a self-publisher, you may not have access to the number of experts involved in a traditional writing project, but you can select a core group of trusted and trained individuals and listen to the feedback they give you. This will strengthen your work and help you grow and develop as an author.