From Wikipedia:
The hedonic treadmill, also known as hedonic adaptation, is the observed tendency of humans to quickly return to a relatively stable level of happiness despite major positive or negative events or life changes. According to this theory, as a person makes more money, expectations and desires rise in tandem, which results in no permanent gain in happiness. Philip Brickman and Donald T. Campbell coined the term in their essay “Hedonic Relativism and Planning the Good Society” (1971). The hedonic treadmill viewpoint suggests that wealth does not increase the level of happiness. Subjective well-being might be largely determined by genetics; that is, happiness may be a heritable trait.
Hedonic adaptation is a process or mechanism that reduces the affective impact of emotional events. Generally, hedonic adaptation involves a happiness “set point”, whereby humans generally maintain a constant level of happiness throughout their lives, despite events that occur in their environment. The process of hedonic adaptation is often conceptualized as a treadmill, since no matter how hard one tries to gain an increase in happiness, one will remain in the same place.
Hedonic adaptation can occur in a variety of ways. Generally, the process involves cognitive changes, such as shifting values, goals, attention and interpretation of a situation. Further, neurochemical processes desensitize overstimulated hedonic pathways in the brain, which possibly prevents persistently high levels of intense positive or negative feelings. The process of adaptation can also occur through the tendency of humans to construct elaborate rationales for considering themselves deprived through a process social theorist Gregg Easterbrook calls “abundance denial”.
Likutei Etzot “Money and Livelihood” siman 27:
צריך שיהיה להאדם הסתפקות להסתפק רק במה שצריך לו בהכרח מזה העולם, ולא לנהג את ביתו כגדולים דוקא, כנהוג עכשו בעוונותינו הרבים בהרבה אנשים. כי אלו שאין להם מדת הסתפקות, עליהם נאמר ובטן רשעים תחסר, כי לעולם חסר להם הרבה….