First I would ask you to define "success."
Self-study will always rely on some material made by others (whether it was specifically made for language education or just content in your target language), and depending on your personality you may be disciplined enough to go through the material on your own, but I think it's very helpful to have a knowledgable guide who can help you understand how to correctly use what you learn. Unless you're incredibly driven and systematic in your self-study approach, and willing to immerse yourself in Japanese language content (like youtube's "Matt vs Japan") you likely won't bear much fruit by yourself.