Zero-sum is dead. In an interconnected world with shared air, shared water, shared information systems, and shared existential risks, what happens to anyone eventually happens to everyone. This is not ethics. This is physics.
For most of human history, you could externalize costs. You could pollute upstream and someone downstream would deal with it. You could create a problem in one place and ignore it in another. That era is ending. Climate change doesn't respect borders. Pandemics spread on airline routes. There is no "away" to throw things to anymore.
When you ask that question, everything changes. Not as a moral slogan. As a structural necessity. The old game cannot persist in an interconnected world. So either we learn a new game, or the interconnectedness itself becomes weaponized and we all lose.