Ponzi is not determined by means of control or profit, but by one simple thing: people put in actual values in the form of dollars, euros, pounds, tangible goods and services... and they end up with promises, faith, hope or empty numbers(like in the case of cryptos). Or simply put: value in - junk out. If you give your iPhone(value) to someone and as a result some number has been modified(crypto) this won't make this crypto practically useful. It is still a number - an abstract mathematical object without practically utility - you can't eat it, drink it, wear it, drive it, sit on it, enter into it, please the aesthetic senses with it, etc. Hence, value in - junk out. And that is ponzi.
You've just proven how confused you are about this terminology. What you've described doesn't refer to a ponzi scheme but to any high risk investment. You put money into a restaurant without doing the research and end up with a place near a smelly canal in a poor neighbourhood. Value in -junk out.
Following your way of thinking, when you put your money into a third party account like paypal only some numbers get modified. They can freeze your account and you get nothing.