The mining economy doesn't make all that much sense even to traditional economics. In traditional economics, a trade takes place when both sides value what they get more than what they give. But if, thanks to cryptocurrencies, a GPU can just sit there indefinitely consuming X dollars of electricity and generating more-than-X dollars of cryptocurrency, then what's a fair price for Nvidia to sell them at? Well, there isn't one; whatever retail price you can think of, Nvidia is better off not selling anyone their GPUs, and just trucking them straight from fab to datacentre where they can mine for Nvidia.

It only makes sense for Nvidia (or indeed any supplier of mining rigs or ASICs) to sell them at all, if they don't in fact believe that mining profitability is sustainable. Every sale of a GPU is a short against all cryptocurrencies.

Peter