Take Leslie White's concept of energy harnessing and control as one of the primary functions of culture. More energy available per capita in a society means less environmental and biological constraint on an individual, thus more options. Cross-refer e.g. Abraham Maslow's hierarchy of needs and self-actualization. More energy = more chance of self-actualization. Question: well-being vs. energy input probably has an optimum point, thus theoretically there can be a statistical maximum efficiency of well-being. Energy added beyond a certain point adds less well-being. Enter gini coefficient - egalitarian distribution at certain (moderately high?) energy values can give highest potential social well-being. Thus theoretical reason for high egalitarian distribution to allow most total sum individual freedom.
Didn't feel like writing the idea in a longer format. Will do so at some point, but had to jot it down.