"I cannot fathom how greed comes into it at all."
But then, I can easily fathom such and wonder what these sellers are basing their asking price on.
I cannot fathom what you think "greed" is, then.
Take an uncontroversial definition (via Wikipedia):
"Greed (or avarice) is an uncontrolled longing for increase in the acquisition or use of material gain (be it food, money, land, or animate/inanimate possessions); or social value, such as status, or power." https://en.wikipedia.org/wiki/Greed
The notion that someone setting a price for used gear that is higher than what many others want to pay is an instance of "greed" suggests to me that we inhabit very different realities.