Consumers are simply one-third of the engine that is supposed to create wealth from money.
The flow of money looks like this:
Employer<<Consumer<<Employee<<Employer...
They are the individuals who make use of goods and services in exchange for the money they have gained (presumably through labor as an employee). The money they provide becomes the incentive for businesses to continue providing those goods and services, which is supposed to continue flowing around the system to the employees and back to the consumer (in an ideal world).
One interesting aspect of this concept is that it has nothing to do with fulfilling basic human needs that contribute to our well-being, except as an exploitation of those needs for money. This system leads to a lot of wasted resources, competition rather than collaboration, and a disregard for issues that are not profitable to solve (such as pollution and starvation).