People who are falling for all this kind of scam just lack cryptographic knowledge, and most of them are blinded by greed.
You don't need no "cryptographic knowledge" to realize that anyone offering you something that is good to be true equals scam. Good old common sense is enough, but unfortunately its not so common.
It is so sad some people fall into cheap scam like this every day just because of greed. Normally recieving a bigger reward of something from a stranger, one should understand that this can't be true to be real but they just fall for it . Some people so believe in it that they see it to be an opportunity that comes in awhile that they shouldn't miss but this is nothing but greed. Nobody will trade or invest for you to return bigger portion of profit, it is just a strategy to get people to scam.