" A growing body of work in social psychology offers a possible explanation for this commercialization effect. These studies highlight the difference between intrinsic motivations (such as moral conviction or interest in the task at hand) and external ones (such as money or other tangible rewards). When people are engaged in an activity they consider intrinsically worthwhile, offering them money may weaken their motivation by depreciating or "crowding out" their intrinsic interest or commitment. "

― Michael J. Sandel , What Money Can't Buy: The Moral Limits of Markets