Self-consciousness is certainly a big factor in the rise of behavioural modernity, although curiously that doesn't seem like a necessary condition of civilization since even ants have virtual theocracies, complete with a slave class.

But perhaps self-consciousness adds to the dynamics of human societies in that we divide into different social classes, depending on how we cope with the existential aspects of personhood, including our consciousness, but also our autonomy, reason, creativity, and ambition.