I was working on a piece recently and quickly spiraled into my own self-doubt. When working on a creative project it is easy to fall into the "who am I to tell this story" hole or "who am I to step in and tell someone how to tell this story" hole.
There is ego to consider on both sides. When you believe in something real and then dedicate time, energy, and sleepless nights to it, there is ego. That is okay and that is ideal. If there is no ego involved there is nothing pushing you to finish or work on a project. You have to believe in yourself enough to take on the task of putting pen to paper or fingers to keyboard. If there was no ego, there would be no piece. Those characters, lands, tales, and spirits stay cloistered in the cave that is YOUR brain. But, capital "E," Ego can be what cripples a project in the time of revision.
For most of us we need some check of that Ego. When working to make a piece the best it can be it is crucial to check the Ego at the door. But that is necessary for the editor, too. Editors must work with pieces that have, clearly, had their heart and soul borrowed, if not stolen for a time, from their creator. It is a daunting task to tell that creator that you think it would be better with cuts or development of characters quickly passed by in the initial draft. The last decision, for most of us, hopefully, falls in the hands of the author. As an editor, this can hurt. As a writer, this can easily inflate the ego. Checks and balances must be accommodated for and that fine line can easily be crossed when working with the wrong editor.