> any stocks that does not pay out dividend is [sic] also a Ponzi scheme
Neither of these things are "Ponzi schemes." Read about Charles Ponzi's role in his investment scheme to understand why.
This is very different from a stock that doesn’t pay a dividend. While you’d never get money out of it if no one was willing to buy it, what stocks generally promise is some amount of ownership and voting rights in a company (which theoretically could result in dividends, if enough stock holders agreed). That said ownership ended up not being valued by other people does not make it fraud. You can certainly feel free to believe that stocks that don’t give dividends are worthless though, that’s a separate question really.
I generally come down on the side that the major cryptocurrencies aren’t ponzi schemes, or fraud in general. (Plenty of fraud in the shitcoins, of course). Ultimately you decided to buy a data point on a ledger in a distributed system, and that’s what you get. But…well, mining sometimes confuses that. Without enough people coming into the system to buy new coins, the miners would start shutting down until none were left. Much like a ponzi scheme, crypto currencies seem reliant on new blood to keep functioning to me. Don’t know if that makes them a scheme necessarily, but they’re more adjacent to it.
For all practical purposes, you could exchange the currency for something else. But that's outside the scope of the staking system as defined.
I'm not making any negative or positive judgement on the system, Ponzi scheme is just a description of how it operates. Similarly, any stocks that does not pay out dividend is also a Ponzi scheme.