Perhaps the major difference between these schemes (scams) and the Stock Market is that 'stocks' are usually based upon legitimate (audited & legally registered) businesses whom are making and / or trading actual commodities, i.e. 'tangible' things; whereas the MO of these schemes (scams) is simply to take money from those at the bottom and feed it to those at the top (albeit with the ruse that there is some sort of forex trading going on, in an endeavour to try and make it look legitimate). Accordingly, the initial success of such a schemes (scams) is an illusion. The early entrants make their money from the eventual loss of later enrollee's.
The question needs to be asked is, if everyone is making money and getting rich, where is all the money coming from? The answer is that it will be coming from the many people that are left hanging at the end of the chain when no one else is either available or willing to buy-in to it, and they therefore the later enrollee's will ultimately lose their 'investment'.
There are those that know & admit that this is a ponzi scheme and yet, so evidently so blinded by personal greed, they still buy into it, thus exposing their total lack of integrity & morals. And so, in terms of winners & losers, it might be said that they are the ultimate losers!