I'm very curious how that can be better then an electrical heater.
It has to be more inefficient as you are not spending energy on calculation but if you substitute it with selling your bitcoins you would need to compensate your co2
It's much cheaper and easier to pay and use NVM than ram. You get best latency for databases across your data.
The prices are already super cheap.
I also not find it easier to buy a lot of small devices instead of one. Your NVM is doing the same thing you do but directly on the controller
Check out the latency difference between sata and NVM.
And yes CPU is idling often enough. Good thing if they have a little bit more io overhead but when you look at PS5 and Xbox, Sony solved this issue and Microsoft is bringing their new storage API to PC.
Similar how music did not change much in the last 20 years