When it comes to antonyms for the term "most self-sustained," several words come to mind. Instead of being self-sufficient, something could be dependent, needy, or fragile. It could also be vulnerable, weak, or powerless. If something is not self-sustaining, it may require assistance, support, or resources from external sources. Alternatively, it may be unsustainable, unsound, or faltering. In any case, the opposite of being self-sustaining implies a lack of strength, stability, or resilience, and forces one to rely on the aid of others or chance situations.