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.
I agreed with you completely because that is the way ponzi cloud mining works some of them even invest your funds into gambling, Forex trading etc in order to meet up.