When people are paid or rewarded for an activity they would otherwise do willingly, the external reward can replace rather than add to their internal reasons, so motivation falls once the reward is removed or feels inadequate. Paying for behavior teaches people that the behavior is something you need to be paid to do.
Interviewed cleaners in a hospital described their work as including comforting patients, reassuring visitors, and timing tasks around patient needs, duties found nowhere in their official job description. They had reframed menial labor as caring for sick people, which made the same physical tasks feel meaningful.
Work becomes meaningful when it offers some combination of discretion, variety, skill development, and a connection between effort and a purpose the worker values. Jobs stripped of these features reduce people to executing instructions, which breeds disengagement regardless of pay.
When institutions assume people work only for money and design jobs around that assumption, they create tightly controlled, incentive-driven conditions that actually produce the narrow, self-interested workers the theory predicted. The false idea manufactures the reality it claimed to describe.
People work for pay and security, but also for engagement, meaning, discretion, challenge, and the chance to make others' lives better; treating pay as the whole story obscures the sources of satisfaction. Fixating on compensation can make the non-material rewards wither even as the paycheck stays the same.
Social science theories function like technologies: once a theory of why people work is adopted by managers and policymakers, it reshapes the structures people live inside and thereby changes how they actually behave. Bad theories, once embedded in institutions, do damage that outlasts the arguments that produced them.