There’s a phrase people use when talking about a task they can do competently: if it were easy, everybody would do it. Publishing, and particularly self-publishing, is like that. If you don’t know what you’re doing, you can try taking the easy (and expensive) path: pay some service to do everything for you. I’m publishing my first novel, so you could argue that I don’t know what I’m doing, since I haven’t done it before. But paying a service to do it for me is not my way, as anybody who knows me will attest.