Every single business following the HYIP model has turned out to be a ponzi scam.
You have the answer to your puzzle,every high yielding investment program is a sort of ponzi schemes which promises high returns and the fact remains that none of that can be sustainable .Never trust anyone that promises to give you any astronomical returns for your investments than the banking investment returns,people who are greedy usually falls for these kind of frauds. Can you provide one good example of a good HYIP you have invested in,i bet you cannot.