I edit books for a living. I LOVE what I do. I feel incredibly lucky that there are people who trust me with their writing. I'm amazed at the courage people have to put so much of themselves down on paper and then share it with others. And, more than anything, I am astounded by the sheer number of people who manage the hardest thing of all: writing the darn thing.
Writers and editors don’t have to agree on everything, and you absolutely don’t have to accept every change your editor suggests. But your editor is there to help you improve your writing. It can be a shock to face a sea of Tracked Changes in a manuscript you had already declared “final,” but remember that your editor’s job is to see what your reader will see. Take a deep breath, then dive in with an open mind.
Are you toiling away at your manuscript, waiting until the big day you finally call it "finished" before you hire an editor? Just because you're not done yet doesn't mean you can't get value from some editorial feedback; in fact, it could save you from unnecessary work and make the whole writing process go a lot more smoothly—not to mention inspire you to keep going.