It's not a prisoners dilemna because you also lose by defecting while everyone else is cooperating.
The thing to recognize and internalize is that the world is a lot more win-win than our psychology has been evolved to recognize. Nationalism, realpolitik, xenophobia - all of these are ideologies that make you poorer and worse off, not giving you some secret insight into the truth of human nature.
Everyone else is not cooperating though. Just because you think nationalism, realpolitik, and xenophobia (and slave labor, for that matter!) are all bad things that one shouldn't partake in, doesn't mean the rest of the world feels the same way, such that they will extend you the same courtesy.
It's a good idea to recognize and internalize this, as it's quite inherent to human nature, and won't be going away during any of our lifetimes.