Agreed on the editing and design, for sure! Use professionals and have a complete and well-done book before you get out there.
However, some people have networks or name recognition or a marketing background that allows them to be able to market their books. I don’t recommend it unless they are sure they can do it, because exactly like you said, it can cost you more later.
But that part also depends on your goals from writing and publishing your book, too. I don’t have a lot of ongoing marketing for my own book, but it is still doing what I need it to, simply by existing.
I’m a ghostwriter, and cannot use the books I’ve ghosted as samples or proof, so I just truly wanted something in my own name out there, as proof I can write a book! Ha.