Speaking as someone who worked for a crypto company, went to the hugely expensive crypto conferences etc.

And ignoring the environmental impact (we should all realize at this point the insane amount of energy that crypto uses. And I really don’t care that some of them are optimizing. There’s so many of the damn things now that it hardly matters)

1: hardware sustainability. I’ll admit, I whined over this primarily because I wanted a nice graphics card to play games and render animations, and now that’s too expensive to happen any time soon.

But, we’re also running into a situation where the physical resources to make this kind of hardware are becoming a bit more difficult to obtain. You think this is just bad for the people who want (need, at this point) phones, computers etc, but it’s also bad for crypto fundamentally. This gap is created now between the people maintaining and updating the blockchain. Only the wealthy few will be able to afford the “farms” required for this

2: it’s a Ponzi scheme/pyramid scheme

I know. This is the one people hate to hear, because it ruins the entire philosophy crypto is supposed to be built on.

It goes hand in hand with the innate value of each coin or token. A coin’s value is so closely tied to the amount of fiat that people have invested in it that it’s impossibly for it not to become a Ponzi scheme. In order for it to be a legitimate currency, it has to actually be pulled from fiat markets and be used independently.

That’s not going to happen though, because they are already making a great deal of legitimate money