I think to those people who got scam by other they do not review the project at all, they do not check the background of the developers, they do not check if there's many people are in it, they do not ask or inquire before they invest they want to got rich in a single day or night that's why most of the people got easily scam.
not reviewing, doing research, and not being selective in choosing projects, and greed for getting big profits in a short time, making people easily trapped in a scam. although it is very clear, currently there are still quite a number of people affected by such a scam. however, the key in this is, to be careful in selecting projects, and doing very deep research.