I see that the owner has been replying to all of those description which is also my thought upon looking to the promised return. All I can say on this matter is that if you don't understand what you are investing, better don't invest at all. Don't invest to the things that you don't understand and it's not clear for you, simple as that.
I agree with you, it seems this is related to bitcoin doubler or known us Ponzi scheme. From which part they generate profit and distribute to their participants or investors? Nothing, because of the fact that after they have a huge fund they will run it away. I learned this because I scammed too many times last year similar to this strategy. I will suggest that investing in bitcoin itself will surely give you a benefit.