Personally, I wouldn't hire an outside editor either. I'd make use of beta readers for big-picture stuff. But I would have my husband (who is also an editor) do a general proofread for typos, because I do find I miss some of them in my own work. However, if you're being published, your publisher will have your work edited - providing you are able to submit something that is in a readable state and has something they are looking for, I don't think there's any need for an outside editor, paid for out of your own pocket. For some people, though, it might be of use in getting their manuscripts up to the point where it is readable and in a submittable state.