Ekstrand: Introducing NVK

You understate this problem in two different ways:

1. Miners probably tend to take better care of their GPUs than gamers (because miners are operating out of datacenters and gamers aren't), so the miners are actually selling a superior product compared to the average person.
2. Miners all abruptly stopped buying new GPUs at the same time, so now there's a supply glut of new GPUs that were "supposed to" go to mining, but were never even opened. On top of that, the 40x series just came out, so at least some retailers will probably try to sell off their remaining 30x cards quickly (IMHO a mistake, because nobody wants the 40x cards at current prices, but meh, inflation could obviate that problem, so we'll see what happens), which in turn implies discounts on unopened 30x cards.

The net result of these things is that 30x NVidia cards are currently a buyer's market, regardless of whether you buy new or used.