How can one conclusively prove that a cloud mining operation is fake though, or a ponzi? Even when it appears impossible you can't be 100% sure that its not someone with a bit too much money doing changetip style donation. Entirely unlikely but entirely plausible.
If you were walking down the street past a bank and you saw a car parked outside in a tow zone with its engine running, and three guys sat inside with masks on and shotguns in their hands, what would you think?
1) They're probably going to rob that bank
2) It's some NRA members with embarrassing facial disfigurements who have got lost and are about to ask me for directions.
You don't have conclusive proof, you are making a judgement based on probabilities, like we do every day in all sorts of situations.
A fake cloud mining operation hasn't disappeared with your money until it's disappeared with your money. It's a bit late and irrelevant to then argue that you gave them your money because you weren't 100% sure they were going to run off with it.
BTW plausible means: seeming reasonable or probable.
