The context of this conversation has gotten slightly muddied, and due to the ridiculous name calling that ensued yesterday, I'm only responding to people who quote me directly on the subject as you have here.
This particular thread of the conversation was prompted by me saying that I don't get the desire to downgrade and sometimes go without a GPU just so that this person can extract the maximum cash from a second hand buyer, prompted by the inclination that the card will be worth a lot less in a few weeks time. Personally, it's not something I would do because a) I want to enjoy my card until I upgrade and b) I wouldn't treat people like that.
It's a personal perspective, and at no time have I said anyone is wrong to do it, all I'm saying is that it's unacceptable to me. I wouldn't sell like that to a family member or personal friend and I'm just not desperate enough for cash that I'd do it with a stranger either.
Of course people can sell whenever they like, and of course the buyer should consider the value in what they're buying. However, there are people who deliberately offload in the full knowledge that the buyer is getting a really poor deal. I'm not one of those people, I see it as no better than retailers price gouging - we're all quick to criticise that.
I was described as sanctimonious yesterday regarding this, and I'll accept that there are people who see it all as fair game and view me that way as a result. That description was fine by me, everyone has different standards & opinions but it's worth being in mind that a discussion forum is a place to share them and we won't always agree.
This guy summarises my thoughts well.