A closer look

Swapping things around somehow makes the world objectively richer without creating anything new. A positive-sum game happens when two parties exchange items they value differently. If you have an apple but hate fruit, and your neighbor has an orange but prefers apples, swapping them means you both end up happier. No new fruit was grown, but total human satisfaction increased out of thin air. It is the basic bedrock of why civilization bothers interacting.