As Jeffe and James both attested, editors are necessary. Dev, line, copy, proof. Doesn't matter which path to publishing you take, having a minimum of two professional editors review your work is not an optional part of the process. In self-publishing, newbies think they can skip the professional edits and save a lot of money. No. No. Nononono.
SPEND THE MONEY, you cheapskate.
You may be an awesome editor of others' works, you may be Marian the Grammarian's sister-from-another-mister, BUT that doesn't mean you can edit your own stuff to the level necessary for publication. As the creator, your brain simply cannot see the flaws.
However, you do need to edit your work before sending it to an editor.
Wait, but, you just said...WUT?
Look, as authors, we all know our first draft is the crap draft; it's riddled with issues. Some drafts are worse than others. It's okay. It's totally normal. It's part of the process. However, DON'T hand that shit over to a professional editor. If you're trad-publishing, you're wasting your editor's time. If you're self-publishing, you're wasting your money. You need to edit that draft.
But, but deadlines...But, but pre-orders...But, but...
But nothing. My friends, I can tell you horror stories from trad-published authors who turned in their "rough draft" only to have it be the one that got printed. Oh, the readers noticed. Oh, the author felt betrayed. Oh, the publisher didn't care. Don't set yourself up for that worst-case scenario. In the self-publishing world, if you send a rough draft to a freelance editor, they may refuse your business or charge you more money. Make your work as good as you can before sending it an editor. That includes having your CPs/Betas take a run at it, then incorporating their feedback. (Scheduling is a different topic for a different day, but don't be a dick and expect 24hr turnarounds.)
The catch is how to edit your work effectively and efficiently without over-editing it. For those of us who are perfectionists or suffering imposter-syndrome, we can all too easily fall into the viciously unending cycle of "tweaking" and micro-edits.
Let the Rule of Threes be your guide.
No book will ever be perfect, but good editors make books a helluva lot better.