I see so many services offering to double, triple and multiple in all possible amounts the coins you put to them. This doesn't sound very convincing to me but some of them are offering the list of blockchain transactions as a proof that coins were credited. Is this pure scam like I think or is there a possibility to realy make some coins? Would like to hear your thoughts and experiences.
Doubling bitcoins has been spread-out in social media, I've almost seen it most of the time in facebook. These kind of sites that offering like this is obviously Ponzi scheme here is the link example of the scam site about in bitcoin
http://www.viral-alert.com/scam-site/ I hope this thing will give you some idea about the scam sites in this kind of industry.