People make this system as means of their living or earning. Even though this kind of system is very dangerous there are lots of people often see this thing a quick money grab. Companies are keep on establishing this kind of model because there are lots of people patronizing this scheme even though it makes other people loses their money or company shutsdown in the long run. Unless people stop supporting this kind of money game, Company will never ceased to exist and prey on their victim.
Many companies have used this system, I have come across a model of these ones that provide a good investment opportunity, they get the funding they roll out a few payments so they could gain the trust of the people, and then simply walk away with the money, a company called Hash Ocean has done this before, it was a cloud mining project and the founder got greedy and walked away with a fortune.