The chances that ethereum mining will remain profitable is very low as you said but what if? Those who buy cards in November 2020 are already at the end of their ROI already, anything is possible but the don't right now is buying those cards at high price
How do you know they sold or are selling their coins, maybe they are holding and imagine if this crashes fast and they even dont have the time to sell when eth is high? or maybe this things crashes and they think is going up again and it doesn't and then they see eth crashing to 100 usd again just like 2018?