Is there any issue with buying a card that was previously used for mining?

If used by a home user who didn’t know what they were doing they might have run it hotter for much longer than a typical gamer so the thermal paste might need a redo.

If used by some miner doing it even quasi-professionally or as a side-gig I’d much prefer it over a 2nd hand card from any typical gamer (most miners) they’ve kept the voltage/temps low and taken care of it far better than a gamer who might be power cycling regularly and definitely thermal cycling even more regularly.

It’s funny how the few who’re totally sold on Bluetooth go “ugh, but then you’d need a headphone jack” as if it isn’t an upgrade for others which wouldn’t affect their ability to use Bluetooth at all.

Your timeline would almost certainly be a little less stupid if you did that with gusto, but people who’ve disagreed with you can also post things beneficial to you or post insights you hadn’t thought of or post advice you’d find useful. I was a heavy RES tagger on reddit and I’d often come across well-meaning or useful posts and comments from people who’d been marked for saying jawdroppingly stupid shit about some other subject.

I know in your example you’re trying to give the right answer or explanation as you see it, but this is also very closely related to Cunningham’s Law:

The best way to get the right answer on the Internet is not to ask a question; it’s to post the wrong answer.

So you’re still providing a service even if it feels bad to have an expert steamroll whatever perception you had. Chances are tons of people had the same vague notion as you and your misguided logic eventually led to the correct path.