I wouldn't trust ebay at the moment especially anyone that overpays. They have up to 6 months to say it stopped working and get a full refund.
If that was to happen , if your lucky you get the card back in similar condition you sold it in.
Worse it did break, and you won't know what they did to break it. So you have a broken card.
Or they scam you completely and post a brick (that is a very low risk)
I would assume a lot, but not all big over payers are mining on them at least in part.
Now mining wouldn't be a big problem if prices were normal, but if the market crashes and the card value drops to normal pricing they could be facing a loss which may make some people try it on with the above options.
Also given the very high temperatures the memory is running on the RTX 3000 series cards I'm a bit concerned mining will start to have an effect on them more than the old RX 4/500 / GTX 1000 series cards .
Not because the ram is running over spec, but the other components and board being heated to 100c + is a lot more stressful compared top the temps the old cards were getting, in the region of 50-85c even on the ram if the miner had setup reasonable cooling.
Mixing usage could also make it worse as the extreme heating and cooling effect over the long term can cause problems with the board contacts.
and use the 1080ti for 6 months
