This is a regular scam method for them... Ordinarily, if you look at their cooked-up testimony, you will understand that those stories are too good to be true. 

How can someone start an investment with about $100-500 and within 24 hours have made about $10-20,000?
Is this kind of story not too clearly fabricated? Yet someone with the right sense will now be convinced that it's true. Go to these scammers and ask them how? And the scammer will have to start explaining rubbish to them about how it works, this and that, and you will just believe them out of greed. Do you know the worst part of it? Most of all this, most of these people on Telegram, Facebook, and Twitter don't even know much about how the blockchain works. All they know is deposit today and tomorrow you will get 5-10× of your deposit. 

People who are falling for all this kind of scam just lack cryptographic knowledge, and most of them are blinded by greed.