I wonder at times whether this is their game, hoping people will just tell them not to bother sending it back and they get a refund anyway.
As for ebay, I stopped selling anything on there years ago, well over a decade, when someone tried to scam me out of a laptop but failed. If something is valuable enough for me to sell, I sure as shit am not selling it on eBay.
More often than not, I give away my valuable tech that I'm done with, because I'd rather get nothing for it, and give it to someone who'll appreciate it than risk being scammed by some scumbag.
This way, friends and family get my hand-me-down PCs, laptops, phones, etc for nothing and they're still, by the time I'm done with them far better than something they'd buy with their budgets. When I buy something, I factor its lifetime in my possession into it's cost, I effectively expect £0 value left in it when I'm done or I don't buy it; everybody wins.