What happens out there in the hurly-burly is not a "zero-sum" or "constant-sum" game. Specifically: it's not a "game" at all. Those games are distillations and models used for testing behavior. This tells us certain things about how people react and interact, but it doesn't tell the whole story.
Going for relative makes sense when you can't take, you can't (necessarily) earn, you can't (in the short term) increase/generate. But you CAN win by destroying. You destroy your opponents resource, thereby "increasing" your wealth in a relative sense. It's why we bombed weapons plants during WW2, no? And to an extent, it's why they salted the earth....