"If you think that something is too good to be true, then it probably is."
Don't mess up with such systems, they are only doubling their own bitcoins, not yours.
These Ponzis/HYIPs have definitely benefited a lot from crypto-currencies.
This is unfortunate but true, the first time I saw a same like that, the scammers were using egold but now they are using bitcoin due to the inability of chargeback a transaction with bitcoin, so the lesson here is we have to even more careful with our bitcoin than with fiat.
we should be more vigilant so that we will not be a catch on them scammers just there and making themselves an alternative ways to earn more money from their bad scheme, and its better to not read their promotion since most doublers posted some appealing promotion so that we will be attract to invest at them and thats a big no! No! To us.