How would you explain the disconnect between German WW2 sympathizers who sold out their fellow humans, and those in that society who found the practice so deplorable they hid Jews in their own homes?

There’s a large disconnect between these two paths of thinking.

Survival and thriving were the goals of both groups.

Just because something is genetically based, and we're therefore predisposed to it, doesn't mean that we'll necessarily behave that way. Much simpler animals, such as insects, are more hard-coded in that regard, but in humans we can override our genetically coded innate instincts with learned behaviors - generally a useful and powerful capability, but one that can also lead to all sorts of disfunctional behavior based on personal history including things like brainwashing.