Angie is a compulsive shopaholic. Every week she shops for new clothes. She has traded in her car for a new one twice this year. After each new purchase she feels fresh excitement for a few days which quickly wears off, leading her to buy something new. Each time she buys something the thrill wears off a bit sooner. This is a classic example of the

hedonic treadmill                                                          

Explanation:

Hedonic treadmill: The term "hedonic treadmill" is also referred to as "hedonic adaptation", and is described as an observed human propensity of quickly returning back to a relative or comparatively stable level of happiness irrespective of major negative or positive life changes or events. The term was initially described by two psychologists named Campbell and Brickman during 1971.

In the question above, the given statement is a classic example of the hedonic treadmill.