Correct, many have been found victim of this trend and its caused by greediness which us a human nature.  Whenever I see many of such promise, I tell myself that,  how do they relate this with their own mindset, that, you send 1bitcoin and get 2bitcoin: you don't trade with this money to say profit is involve, so, those greedy humans can always fall for this type of scams around this industry. I say never you send anything to get double of what you set: its arrant scams and should be avoided.