You're equivocating on "ingroup/outgroup psychology." If you say that every split between groups is based on that psychology, regardless of the groups' contents, you'd have no basis for importing an evolutionary reading of that division. You'd be talking, rather, about something like the metaphysical possibility of multiplicity. Alas, evolutionary biology doesn't own the concept of differences between groups, classes, or sets. That's a much more general concept.

However, if you're talking about the narrower, evolutionary sense, your reduction no longer applies to the distinction between philosophical elites and unreflective masses, assuming the elites don't behave like monkeys defending their territory and transmitting their genes. Indeed, those elites are often ascetic and celibate. The differences between these two groups is cultural rather than biological, so your reduction doesn't go through so obviously in this case.

Moreover, if this particular ingroup/outgroup distinction is anomalous and irreducibly cultural with respect to the behaviour of the two groups, this distinction isn't "in my mind." It would be in the data that belie your attempt at greedy reduction.

There seems to be a contradiction between these two statements of yours that you wrote back to back: "I am saying it’s the same underlying psychology. Only philosophers or religionists would imagine that one can go into their mind and find a path to transcend humanity."

The first sentence posits the reduction of culture to evolutionary biology, which is to say it presupposes sociobiology. The second sentence posits the opposite, that there's something anomalous about philosophers and religionists. So your second sentence takes you in the direction of my analysis, and away from your first sentence.