The thing I like about individual sovereignty is that it's bottom-up rather than top-down. It's not a system. It's something you decide to pursue, regardless of the system. Moreover, the decision is yours solely, without anyone having to cooperate with you, although cooperation helps, but it can be done at any scale and any level, not just political and "51%" like democracy. And the further you get and the more people follow suit, the less powerful the system becomes.