that is what i mentioned in my reply this OP is just creating a scam scheme , because in this he is clearly explaining that if he gets enough bitcoins then only he will pay you double if not you have to wait, in this what is his benefit, so it is clear that he will be waiting and when enough amount of bitcoins he gets he will just runaway with the balance bitcoins and mostly he will reply that fund is not enough to pay back. and after some time the site will get expired and he will run away.