That's a false equivalence. Fiat currencies are used FOR Ponzi schemes of course. But they are not THE ponzi scheme.
The question is, do you believe in the inherent usefulness of a specific crypto? If the only way to make money from a crypto is predicated on other people putting more money in it later on, that's the definition of a Ponzi scheme.
You don't hold onto euros and dollars because you think you can sell them later on for more money. That's why central banks have inflation targets: so that you're incentivized to use currencies as an exchange instrument, not as a store of value.
> That's why central banks have inflation targets: so that you're incentivized to use currencies as an exchange instrument, not as a store of value.
A bit off-topic, but why is that a good thing? Why is it better for currency to lose its value over time? I'd imagine this leads to people mindlessly buying more and more stuff, to use up that money before it loses its value.
On the other hand, if value of currency would increase over time, then people would have to spend it only on whatever they actually really need or desire. Is that bad?
> I'd imagine this leads to people mindlessly buying more and more stuff, to use up that money before it loses its value.
They don't spend it mindlessly, they still allocate it relative to other opportunities. Low but positive inflation makes a lot of investments relatively more attractive, therefore incentivizing people to invest in economic activities, instead of sitting on their cash. Deflation creates a dearth of resource available to invest.
Plus it's a redistribution mechanism. If all you have to do is to sit on your cash for it to grow, then it's a rich becomes richer system. If you have to invest that money, there's an uncertainty, a risk, and opportunity for people to multiply their starting capital.
Some early bitcoins buyers are saying exactly that: "I got in early, I'm set up for life, if you didn't get early enough too bad you're gonna stay poor". It's not really how we'd like an economy to function.
> [...] people would have to spend it only on whatever they actually really need or desire. Is that bad?
It's bad if you want a growing economy. And usually technical innovation comes from relatively niche investments that no one really needs right now.