Wasn't this the premise of a Black Mirror episode?
Well, unlike in the TV show, this scammers are bluffing and they don't actually have anything on the victim, so you would have to be a special kind of gullible to believe someone without any kind of evidence (and send them money on top of that).
There are hundreds of malwares that ask for bitcoin as ransom, which are in my opinion more dangerous than this one, I don't think this deserves the attention it is recieving.