The key, of course, is to use the right tools. It has to be a quality book, professionally designed and edited, and you have to actually think beyond simply getting the darn thing in print.
Having gone through seven rewrites on a manuscript I'm hoping to sell, I can certainly understand how professional assessment and editing would be useful! Sometimes it's just so hard to see what needs to be done and having a consultant surgeon pointing out where to put the knife has got to be good (if painful). I'm very grateful for my wife and other writerly-inclined friends for providing that outside view. This time around, I'm working up a very clear plan before I start writing the book. That way it's much less effort at the tidying up stage!
I guess that's the kind of wisdom the publishing industry experts can help with. It's not until you've been through it that you realise what you need. You've got the scars, but can see how to do it differently.
If I can, I think I'd rather have my operation performed by a specialist surgeon. But of course, a quality self published work will do better than no published work at all. Who knows? Perhaps I'll pick up a scalpel yet.