These companies are like banks. They don't hold your coins like they should, they invest it and try to make profits with it. Now while price chart is going up that huge, many customers try to get out their funds and they simple don't have it anymore. You have to wait a couple of hours/days/months until new users added funds to pay you out.
Yes, That is like a Ponzi scheme. They must wait for another customer to join and deposit fund then it will return back to previous customer.
if no, it will return to scam. Be careful with this kind of games.
