They keep recruiting new people to the group

each bring certain amount of $$$ and promise a huge return in a fairly short of peorid of time.  The money will not be invested to any meaningful project but to pay the peole joined earlier in the game.  Depending on the number and layer of "investor" one brings in, they will give you different type of "title". such as "director', "banker" etc... 

When they recruit new members, they will pay the expense of travel, decent hotel and food to create an impression they their operation is so successful.  Often, they will tell you that they are sponsoring of a project that has been approved by authority, they can show you some picture taken with government officials as proof.  In fact, the picture was created by PS and the roject does not exist at all.  Well, this is what happened in Xi An and Guangxi a couple of years ago.  It seems that some smart guy try to repeat that here.  They know it is illeagal so they have to ask you do it secretly.