This critique is basically saying that cryptocurrencies have Ponzi-esque economics or more aptly named greater-fools economics. The argument being that as they have no cash-flows, any appreciation must come from future investors piling into the asset. I think this is a great optic to look at the problem as it focuses on the economic design, its sustainability, and its valuation in terms of future cash-flows.
Nevertheless not all cryptocurrencies satisfy the above. The prime example being Ether. In the last year it has experienced -0.186% circulating supply inflation (i.e. it's non-dilutive to its holders) [1]. While the network has captured around USD 6.5M per day ~ 2400M per year in fees due to its usage as settlement layer which are paid to its stakers. Basically, it's cash-flow positive and does not rely on greater fools to sustain its economics.
What you are saying is you can invest Ether (i.e., stake it) and then might earn a return in Ether (not USD). Any appreciation of Ether vs USD still needs to come from outside demand for Ether.
(Replying to PARENT post)
Nevertheless not all cryptocurrencies satisfy the above. The prime example being Ether. In the last year it has experienced -0.186% circulating supply inflation (i.e. it's non-dilutive to its holders) [1]. While the network has captured around USD 6.5M per day ~ 2400M per year in fees due to its usage as settlement layer which are paid to its stakers. Basically, it's cash-flow positive and does not rely on greater fools to sustain its economics.
[1] https://ultrasound.money/ [2] https://charts.coinmetrics.io/crypto-data/?config=JTdCJTIybm...