I don't have studies at hand to cite, but there seem to be a growing number of them indicating or demonstrating that a significant portion of humans' cognitive

I don't have studies at hand to cite, but there seem to be a growing number of them indicating or demonstrating that a significant portion of humans' cognitive ability goes into making (instantaneous, sub-conscious) comparisons. Contentment seems to be more a matter of "keeping up" and "as good as" than some sort of absolute measure. From an evolutionary perspective, this might -- speculation -- involve the individual ensuring they are still valued by and a member of community. If you aren't doing well within the community, you are at risk.