We just "upgraded" our house with a bunch of second-hand IKEA furniture, buying their typical drawers and bookcases for $20 each using Facebook marketplace.
Considering that buying a new piece would be $200, and a used one is $20 and already assembled, and I had to drive 1 mile down the road to pick it up, it was a win.
Now say I am a seller though. I have a bookcase for 200, and it is gently used so I'd get 40% credit back. That's $80, which is of course better than 20, but it would require me loading the fully assembled case into the car (on top of the car?) and driving it to Ikea, all for an additional 60 bucks gain. If I have the car, and able to move it, and have the time, 60/hour is still a good "income" for a lot of people. But boy that's a lot of work for a one time benefit, and most Ikea pieces that can be car-transported when assembled don't even cost 200 bucks.
It's hard to imagine a lot of people going through the trouble, when they can just sell it for a few bucks to a neighbor and forget it.
On the other hand, if you get UHAL, grab 10 bookshelves, pickup and deliver them all to IKEA on the same day, now that's $500 in profit. Someone could make a good side hustle out of it.
Anyway, we shall see.