While they while promising fast gains with small investments I think they will continue to have success because the human being is to greedy and when such an opportunity is presented to him most of them are blind.
Those type of scams were going on even before crypto and were called ponzi scams.
We should take matters in our own hands and do a correct research before investing some money and always keep in mind this: "If a thing sounds too good to be the truth than it might be a scam. "