I think this topic has been on my mind for some time. Editing is important; after all, we want to put the best published book out there to see success with our writing. This is most true with a narrowly focused subject such like publishing a book on Transylvania.
Where would we be without an audience?
If we annoy our audience or write and then publish a first draft (which is not "publishable"), then we run the risk of making our readers not want to read our books. This is one of the reasons for editing, but it should not be the only reason. A person with some detailed knowledge of the subject is able to point out to the writer any factual mistakes they might have made.
Take, for example, the picture below. A writer who, in a rush, labels this as a map of Romania before the Second World War would likely lose a lot of credibility if that is published in an e-book. However, when an editor sees the error and fixes the caption to read "Map of Romania After WWII" (as shown in the graphic) then it is not a loss. That is why we writers need editors.
Our audience makes us, and also can break us — in this example, they likely already know a lot about Romania, Hungary and Transylvania.
This is why we have to edit, and pay for an editor or three. (I personally think two editors — one for copy editing and one for content checking.) This is most true when we self-publish a book, otherwise no matter how "ultimate" we think our self-published book is, if it is not edited, then we have a problem.
And our audience will tell us.
We owe them a book that is well written before it is published, and this means proper edits; this means a better published book. In the long run, our readers will thank us. We need edits to create a better published book and its reputation will then build itself. This is true of any book, and I've seen it first-hand with In Search of the Lost Ones.
The better the edits, the more likely that the book is a better purchase for our audience, and this means a bit more money in a writer's pocket. Paying for editing might sometimes be a hard pill to swallow, but in the end producing a better book is much more important.