I fully agree with your point. However, this only applies when miners are buying new cards. I live in Vietnam, crypto mining/usage is pretty big, during the last crypto craze a few months (a year?) ago, all miners are willing to buy old cards, used cards, even broken cards at high price, I sold my 570 for $300.

Furthermore, flashing custom mining BIOS, what I’m told is that every miner here has to do or it wouldn’t be profitable, voids warranty.