Btw. Let's not throw psychology into this. I've taken psychology. I've studied human behavior and the behavior of animals and such. Even illogical people are logical and predictable in various ways. There is order even in chaos and chaos even in order.

I think the githyanki are crazy. They are psycho nutjobs for serving an undead lich queen and they do so very vehemently. This is established lore. They are crazy, intelligent, and very dangerous, and they serve their queen zealously.

But even their insanity has rationale to it. They are driven and insane because they are sold out to their belief in their lich queen. As such, a gith who does not act in an extreme way to serve his lich queen and gain glory for it, is acting contrary to how he should act using his own people's logic and reasoning.