Here's a pretty good nutshell rendition of the rise of consumerism from a DailyKos diarist. The writer emphasizes the viral spread of materialistic desire once it became clear that mass production would require a broader consumer base. How a person regarded herself became a matter of what one owned rather than what one did, particularly because meaningful work wherein craft was respected was replaced by monotonous, industrialized work, micromanaged into limited, joyless, repetitive tasks. Shopping became the forum wherein the promise of democracy was theoretically fulfilled -- anyone can own a TV set, a car; anyone can take a trip to Disney World. But the invidious comparisons that ranking oneself by what one owns (rather than by what needs are sated -- if those "needs" aren't always already a pretense, as Baudrillard argues) invites leaves us perpetually unsatisfied and insecure in our place in the class structure.
The key mechanism seems for consumerism seems to be the externalization of happiness -- pleasure is made elsewhere, it becomes something you must buy rather than a state of mind or an approach to life, an openness to situations and other people, a curiosity. Pleasure industries (lifestyle gear, entertainment, recreational food, etc.) therefore always try to romanticize passivity as convenience, freedom from the unpleasant necessity to think or deal with other people, though consumers often subvert industry's intentions -- inevitably so, because such subversion is the sign of life, and we are all biologically programmed to try to stay alive. But the seductiveness of consumerism remains a constant hum in the backdrop of American culture, promoting values that otherwise seem alien but are implicit throughout the entire retail buyosphere that constitutes virtually all our public space. Sociologist George Ritzer deduces the idealogical imperatives behind our "cathedrals of consumption": "Speed, efficiency, self-service. and limited interaction get to the heart of many of the new means of consumption....These are largely American innovations and therefore reflect American values." So the American values that we typically trumpet -- freedom, opportunity, democracy, equality -- are all really subordinate when we come to which values are actually enshrined in our shared institutions (all of which are by and large commercial enterprises).