Final answer:
Lemuel Greene's unhappiness despite high income can be explained by the hedonic treadmill theory, relative deprivation, and the self-determination theory which all suggest that factors beyond wealth contribute to individual happiness.
Step-by-step explanation:
Several theories can explain why someone like Lemuel Greene could be unhappy despite having a high income. One such theory is the hedonic treadmill theory, which suggests that people quickly return to a relatively stable level of happiness despite significant positive or negative events or life changes. Another important concept is the notion of relative deprivation, where individuals may feel discontent when comparing their situation to others whom they perceive to be better off, leading to feelings of inequality. Finally, the theory of self-determination emphasizes the role of autonomy, competence, and relatedness in happiness, indicating that wealth alone may not satisfy these intrinsic psychological needs.