The question makes an assertion (proposition) that is false.
- The optimum group strategy is ethnocentrism.
- The optimum political strategy is political ethnocentrism.
- The optimum economic strategy is intolerance for competition against ethnocentricity,
- The optimum legal strategy is rule of law (reciprocity) that enforces non defection against ethnocentrism by a prohibition on internalization of costs and externalization of returns.(Socialization of costs, and privatization of commons).
As far as I know it is impossible to find evidence, or argue logically, otherwise.
Everything else is a justification for parasitism by the commercial complex, religious-academy complex, or the state-tax complex.
The left violates every one of those principles in order to dismantle meritocracy and ethnocentrism and to reduce us to socialist poverty – the poverty that ethnocentrism and rule of law evolved to raise us out of.
This is the problem with the American Model of a Purely Market Society: without ethnocentrism it is simply suicidal, since without limitations, the commercial, religio-academic, and state-tax-bureaucracy are incentivized to destroy the host population. (And therefore they do).
The Returns on Ethnocentrism are multiples of every other possible strategy. Just how it is.