How can people believe in this kind of scheme? if someone did that kind of scheme then that person would be running a ponzi scheme, and I doubt any celebrity or anyone famous would do such a thing. Then I ask the same question again: why the hell do people fall into scams like these? The only answer that comes in my head is: greed
It's not just about greed, but about ignorance combined with poor English knowledge with the addition of something very important - some people blindly following some celebrities on social networks and they will do whatever what is required. Ponzi is an unknown term for them, therefore they can not even defend themselves from any kind of fraud.
These types of fraud are very easily feasible, you only need FB/Twitter account with name as much as possible similar to the original and coin address - then you just throw the bait in digital sea and catch digital fish. As long as there are possibilities, there will be the fraudsters who will exploit them.