Capitalism and Consumerism-An inextricable relationship

To keep the economy growing, people must keep on consuming. Advertisements and other media show products that would make people 'unhappy' unless they have them. So we are living in a society of consumerism. We are buying more than we need, and we are never satisfied with what we have. We would be more happy and less broke if we 'break out' of consumerism and the standards the media has set.
But is it that simple?
Is sustaining consumerism for the growth of the economy? I would rather put it that it's to keep the economy from collapsing. The development of technology has brought an abundance of products, and the products need to be sold, in order to earn the profit a company needs to pay off the expense. If people start consuming less, sales will go down, companies would lay employees off, the layed off employees would not the money to buy products, and the situation will get worse. This is what caused the Great Depression of the 1920s.
The desire to buy, or the superabundance of products-which comes first is hard to know. However I think that the scale of the economy now relies on excessive consuming and the endless desire to have more and have better. This is where the millions of ads and media exposure comes in. Each ad may just be promoting their product, and dramas(such as Sex and the City)and reality shows(such as ProjectRunway and America's Next Top Model) may just be trying to please sponsers. But on the whole, it works as an effort to not stop the cycle of consuming and producing. Or otherwise, the whole system may crash down.

Of course I am not saying that consumerism is 'inevitable' and we should just live with it. I myself try not to buy things I really do not need. I am exposed to ads, dramas, and other media, and I have my own list of what I would like to have-but I try to think more before I consume. However, I just wanted to point out that by just changing how people consume will not solve consumerism-the structure of the economy itself may crash down even before consumerism does. Little changes made can be effective on a long run, but I think the 'producing' part may have to change. Small stores spreaded out rather than big retail stores, independent producing and catering rather than one large source of products may be an alternative.