So you deny there's a dominant form of game theory? I take the dominant form to be the one assumed in that Stanford Encyclopedia article I quoted from earlier, the one that acknowledges the original model has been added to for different purposes over the years, but that nevertheless goes back to von Neumann and Morgenstern.
According to the article, that conception takes rationality to be, in part, an assessment of outcomes with respect to their contributions to the agent's welfare. That's the point about egoism. Rationality is meant to be an expression of self-interest, because that's its primary, evolutionary function.
Of course, it may be in our self-interest not to be selfish and even to give up on our search for happiness and to live as monks helping other people. That would be closer to rationality in the higher, spiritual or more existentially evolved sense. This is roughly what I argue in "Happiness is for Sheep" (second link below).
But original game theory assumes we strategize to compete with those who scramble to enrich themselves with access to limited resources, because we're essentially no different than them. That's obviously the capitalist, social Darwinian view of human nature, too, going back to Adam Smith's point about the invisible hand. We can cooperate and form alliances (as in social contract theory), but we do so out of self-interest, not empathy or altruism or any higher, transcendent outlook such as one obtained from peak states of consciousness or religious experiences.
Anyway, we agree on more than that. I see from your blog that you're a Never Trumper.
It was a pleasure dialoguing with you.