The people behind are too big to come with a ponzi and scam anyone

Ponzi works especially well when it's organized by the big ones. You must have missed a lot in the history of scams in the last god-only-knows-how-many years (https://en.wikipedia.org/wiki/List_of_Ponzi_schemes). Even the "Ponzi" (yes, the guy who's name become the keyword for those kind of schemes) could easily be classified as a "big one" when his business was at the peak (https://en.wikipedia.org/wiki/Charles_Ponzi#Securities_Exchange_Company)