Well, isn't also the case that a toddler still hasn't fully developed their empathy and other mental faculties, and thus aren't capable of understanding the full extent of how their behavior affects others (and indeed why they should care).

I'm not saying that anyone should feel ashamed to negotiate for better compensation (quite the opposite!), but I'm also not sure that you can look at those little uncooked narcissists and conclude "this is how a human being naturally behaves". I think it's pretty normal for a person with mature emotions to feel at least a bit bad when making demands.