This explanatorizing is mired in 1960s Mickey-Mouse verbalisms devised by British (possibly drunk) naive statisticomaniacs.
Because of scaling, arguments for the survival of individual(s)≠survival of groups. So you need to explain groups qua groups.
+ Studying the psychology of individuals will never allow you to understand that of the market (determined by extremes, not sum).
+ Rationality for indiv. does not translate into "rationality" for group.
Saying it the way it is:
Evolutionary biologists are dumb.