In spite of our spontaneous feelings of horror, we care little if 'one of those little dots stops moving', as Harry Lime put it, and admitting this to ourselves is painful only in part because it cuts across those feelings. In large measure the cold child comes from the recognition that others care no more for us than we do for them, and that our warm protestations of altruistic intent, and theirs, are supported only by feelings which we can so easily reason in nothingness, and by the less impressive, though very sound, policy of doing as you would be done by.
And if ever there were pointless knowledge of no utility, then this is it. After the outrage to our emotion and psychological frostbite of reaching this moral absolute zero, we find that our behaviour does not and cannot change at all; our selfish beset interests are best served not by a diabolical nihilism, but by carrying on as before. There are no ethical foundations any more than there are epistemological foundations; what of it?