This is the normal economist understanding for how things should or aught to work (Ford paying his workers so they can buy his cars), but it is not necessarily how they must work in practice.

Colonial economies did not require the lowest earners to contribute to demand nor Rome when it transitioned from small farmholders to consolidated farms and slaves, or modern gulf states. The examples are arguably unhealthy as economies long term, but practically they may persist for fairly long periods of time.