Are Book Editing and Formatting Services Really Worth It?

I’ve been debating whether to invest in professional book editing and formatting services , but I’m unsure if the results justify the cost. Do these services significantly improve a manuscript’s readability and publishing success, or can skilled writers manage fine on their own with software tools? I’d love to hear experiences positive or negative from anyone who has hired editors or formatters. Did it truly elevate your book, or did it feel unnecessary?