Not necessarily one or the other is right, circumstances vary.

Sure, the price of the HDTV example will likely come down. But that means a year or two without it. Is the year or two of 'denial' worth the money spent? That's simply a personal choice. Extremes of either behavior can have negative effects, one can squander one's resources and have nothing (at one extreme) or there are cases of people dying, living in seeming poverty even though they had plenty of money in the bank.

Early human societies were optimized around one model or the other.  Hunter gatherers needed to live largely for the moment. A major prey kill, or a bountiful crop of wild food meant you eat it then (as well as share freely with the group). In essence that society favored reciprocal generosity. By contrast, agricultural societies needed to take the long view. Planting crops long in advance, raising animals (which temporarily consumed resoureces) for future benefit. Protecting those resources over extended periods of time created a more cautious environment, with trade balanced on a more structured value level.