Xenophobia?

[Angrboda]

Well, those who have more will always, always be scared of those who have less.

Once you've gotten hold of the bone, there's no way you letting it go just like this. Never mind how exactly your society got to be where it is, forget colonialism, forget exploitation, forget selling a whole bunch of countries to the Soviets, so that you can save your own asses and enjoy your nice, entitled lives.

Just keep your dirty mitts off our grub!

In behavioral economics, the endowment effect (also known as divestiture aversion) is the hypothesis that a person's willingness to accept (WTA) compensation for a good is greater than their willingness to pay (WTP) for it once their property right to it has been established. People will pay more to retain something they own than to obtain something owned by someone else — even when there is no cause for attachment, or even if the item was only obtained minutes ago. This is due to the fact that once you own the item, foregoing it feels like a loss, and humans are loss-averse. The endowment effect contradicts the Coase theorem, and was described as inconsistent with standard economic theory which asserts that a person's willingness to pay (WTP) for a good should be equal to their willingness to accept (WTA) compensation to be deprived of the good, a hypothesis which underlies consumer theory and indifference curves.

— Wikipedia:

Ownership endows value by its own virtue, and nature has endowed us to hold dear what is ours. Why? Evolution. The endowment effect begins with the natural propensity for animals to mark their territories and defend them through threat gestures and even physical aggression if necessary, thereby declaring the equivalent of private ownership to what was once a public good. The evolutionary logic runs like this: once a territory is declared taken by one animal, would-be trespassers have to invest considerable energy and risk grave bodily injury in attempts to acquire the property for themselves, so there is an endowment effect. We are more willing to invest in defending what is already ours than we are to take what is someone else's. Dogs, for example, will invest more energy in defending a bone from a challenger than they will in absconding with some other dog's bone. The endowment effect with property ownership has a direct and obvious connection to loss aversion, where we are twice as motivated to avoid the pain of loss as we are to seek the pleasure of gain. Evolution has wired us to care more about what we already have than what we might possess, and here we find the evolved moral emotion that undergirds the concept of private property.

— Michael Shermer, The Believing Brain

(See also Kahneman and Tversky's work on prospect theory.)