I don't know if I would say it dominated the 1920s, it was just more present than ever before, or more possible, so the contrast was also more noticeable.
In the present day, I think we are much more materialist. We work harder, earn more money and spend more money. We surround ourselves with material goods and every Christmas season, we get very unreasonable with our spending habits. It's one of the things that makes reading The Great Gatsby more relevant than ever for today's students.
In accord with the previous post, the greed that characterizes The Great Gatsby is only that of the nouveau riche, the rich, and the costra nostra. For, the average American made only $2000.00 a year. After World War I, values were conservative. There was some spending to be sure as the Ford, which could be mass produced, became the car of the middle class. And, the radio produced a huge craze. The radio not only reported the news, but it helped to shape it as with millions listening to it, radio's messages could help to solidify the chauvinism of the country, making people feel that they were in unison with thousands of others in their beliefs.
Certainly, radio advertising was responsible for the consumer culture. Some historians feel that the false advertising of radio contributed to the ignorance of the American people towards anything unpleasant. Thus, the illusions that radio created helped to "make Americans so mentally unprepared" for the Stock Market Crash of 1929.
In Fitzgerald's novel, the character Gatsby exemplifies this type of American who ignores the darker side of reality. Gatsby's attitude is not so much one of greed as that of the illusion of the American Dream. This mental unpreparedness for reality is as much a part of the Jazz Age as that of the spendthrift wealthy.
If you are talking about this book in particular, then I would say yes. I think that Gatsby's party guests and Myrtle are the best examples of this. They want to be rich or live the lives of the rich, regardless of whether those lives are empty.
However, if you are talking about the 1920s in general, I disagree with this idea. I think that it may depict the upper class, but it did not apply throughout American society. Beneath the rich who acted like Gatsby's "friends" during the "Roaring '20s," there were lots of common Americans who were much more interested in trying to maintain traditional values. (This is, after all, why the KKK was so strong in the North during this time.)
Fitzgerald is only portraying the upper class. For whatever reason, our vision of the '20s as "roaring" focuses on that class only.
I think that this is the setting upon which Fitzgerald is making a direct statement. The flapper generation or the time period of the Jazz Age where there is so much obsession with wealth and its trappings are what Fitzgerald indicts as preventing a full embrace of both dreams for one's consciousness as well as understanding people as ends in of themselves and not means to ends. Fitzgerald was able to dissect this culture very well in the book. His depiction of Tom and Daisy, Jordan and Myrtle, as well as the entire social realm where individuals cannot see past superficiality is something that precludes full and lasting happiness. When seeing the work in the historical context of the Great Depression that follows the Jazz Age, Fitzgerald's insights on the consumer culture and its material end might be even more relevant. In the end, as much as characters in Fitzgerald's work valued wealth and privilege, the looming economic crisis that America and the world would endure undercut all of this, and shattered such facades of happiness. In the end, the monuments built with beliefs of material obsession and consumerism were ones of sand with the historical tide coming into wipe them away.