Answer :
Consumers are buying more products because their need is created by marketing, there is a trend for a product or there is a special moment that a particular product is needed among some group of people. Continuality of selling a product can be also achieved by producing its newer versions - sooner or later most of the consumers will feel a need to own newer verseion (or they will wait for another newer version). Good example of that is what happens to iPhone sales.
