It's very easy for cloud mining scams to last because they don't really need new investors to pay old investors.
They can just take your money and give it back to you a little bit at a time.
They go until the deposits stuff and the owner realizes they will never have more money than they do at the moment, so they run.
They´re probably enticing the current members with offers to reinvest. That´s one way these schemes prolong their existence. And there´ll be discounts on hash sales. At some point these very promising offers come thick and fast which is usually a sign that the end is near.