: SDF: This term "self-interest" is meaningless, whether used by Gee or Red Deathy or anyone, because it tells us nothing about the underlying motivations of behavior.
It matters in the context that the person undertaking whatever action believes it to be in his/her self interest. You decide the value and act upon it. There is no hard prescription for what self interest must be, its a reinforcement that perceived self interest is the prime motivator and that the idea of 'selflessness' is an illusion, or at best a confusion of terms.
: pompous-asses who think they have discovered something "essential" about "human nature".
Just as the pompous asses who think humankind are 100% shaped by environment and have no 'human nature' whatsoever.