If the demand for a commodity increases, consumers take more of it and the supply decreases. Therefore, the producer must increase the supply in order to meet the ever-increasing demand. As supplies decrease, the demand for it grows even more, thus creating an "upward spiral" that will cause unpleasant results.
Equilibrium is only met if the cycle of supply and demand is stable - causing no upward spirals. In an ideal state of equilibrium, supply always meets demand. There may be some fluctuations to this balance but not enough to create an upward spiral.
Humans need the planet's natural resources. Nothing can be done to change this fact.
In this planet where supply isn't infinite, an upward spiral would be inevitable. Supply will run out and it wouldn't be enough to meet the demand. The consumeristic instinct of humans drive them to create more of this supply but at this rate, the resources needed to achieve this is running out. So how do we solve this?
Eliminate the demand. If the demand is lessened, there will be enough supplies to satiate it. Whatever supplies that are left will be given to the remaining humans who deserve it.
Eliminate the population. Achieve equilibrium.
