Many "scams" start as legitimate ideas which, at some point, are unable to generate the "guaranteed" return. They start making the return by giving new investment money directly out to older investors to make up the gap, and voila - a Ponzi scheme is born out of necessity, not even out of intention.
Just stay away.
If I were to join a real estate group, I would (1) be involved in selecting properties myself, (2) receive COMPLETE financials, and (3) only join under the model where we all make $$ or eat it together.
