It seems that narcissism is at the heart of network marketing... esp. the "successful" ones.
the scammers are sociopathic narcissists
Narcissists are supremely confident, and have a sense of entitlement. Everything is about him/her. Any conversation will be steered toward him or her, even when it's about you. S/he needs social proof, and social adoration (from sheeple, generally). This is the kind of people that post-hoc justifies his/her scamming "They knew what they're doing, I never told them to invest more than they can afford to lose".
the victims are neurotic narcissist-wannabes
They mistake a 'deaf ear' and 'blind eye' for confidence. They train themselves to be narcissists (just like their sponsor/upline) but instead is adoring / edifying their upline... and paying into the system.