The principle of existence of "Pyramid schemes" is based on the effect of "Sancho Pancho". The psychology of poor people is that the more you promise them, the more they believe it. Greed for gain switches off poor people's critical reasoning.
Generally,they are good and smart people, but some of them are blinded by greed and itch for gain, others become slaves to their delirious illusions. They are all so different but the thing in common is that they are all slaves to their passions.