Market value plus price manipulation by the banks and elite to scare regular people away (the only way they can harm it) makes it volatile, and volatility makes it possible to earn huge profits, if you're lucky.

That leads to scammers entering the space, advertising their own services, which is often just a version of N**erian prince letters, or various methods to make you create a wallet where they control the keys, allowing them to steal your funds.

That's not the same as a Ponzi scheme, in a Ponzi scheme new investors bail out the old ones until the whole thing collapses. Sure you could say market value is like a repeated Ponzi scheme, but that would be one of those retarded ideas that keeps you so scared of all forms of investments and market value, that you just sit there with your monopoly fiat currency and watch it lose value at constant speed.