I think it’s less of a problem that they run at full tilt, more a problem that their value decreases significantly with age. In 4 or 5 years, they are out of date and not worth much. So there is a constant need to reinvest in newer faster gpus.

So, yes, if they collapse, then they can sell them but not for much. Even without a price collapse they are worth a good deal less. With a price collapse they will be worth much much less. Possibly close to worthless if the market is flooded.