You don't need to be 100% self-sufficient if you build a community to trade and cooperate. Division of labour is better.
But you do need those community ties to be strong enough to prevent rats and feds from destroying it.
Discussion
Self-sufficiency is a scam, but building a strong community akin to what you are speaking about is incredibly difficult. It's a goal to aim for to be sure, but actually getting there is not easy, even for the most courageous and determined among us– Because inevitably you must rely on others, and they are inherently unreliable compared to your self.