In my opinion, as someone who studied Behavioral Economics quite a bit in undergrad (and this is precisely the kind of shit we went over), it is really just an desperate attempt by economists to rationalize marginal utility theory and justify consumer manipulation. You have to basically take the concept Utility as normative, thus the purely atomistic individual, and then use descriptive means to try and explicate deviations from the norm.

In short, in order to talk about altruism you have to contrast it with an a priori assumption about nonaltruism as the default mode of decision making. That ain't so simple, humans are dynamic, social, and qualitatively diverse decision makers, we also have a conscious and unconscious which are not some purely harmonious unity. I think the most disconcerting thing for most people, what the libs are incapable of grappling with, is that our perceived self-interest rarely actually ever is simply that