This thread makes me happy, and is very much in line with "run your life like a business to gauge whether it's working for you or not".
Decorations of any kind. I spend ~$120 for two foreign-style round plate decorations to go on both sides of my TV. I love them, but I guarantee you nobody would want to spend more than $20-40 on them second-hand. I've had them for maybe a year. I also watch a lot of urban exploring videos on YouTube, and the decorations are almost always still there at abandoned houses.
Semi-cheap furniture. Bought a $130 end table for $25 at goodwill. Bought a $120 printer card for $30. They were somewhat lucky finds, but they are last-five-years-style in decent shape.
Movies. VHS tapes go for $0.50, some people have to give them away for free to get rid of them. Granted these are from the 90s, but most people paid $20 for each and put that on a credit card. It's not uncommon to see hundreds in collections at garage or estate sales, and $20 was worth more back then, too.
Dining sets and collectibles. Someone mentioned it's a generational thing, I agree. My sister and I had no interest in potentially having our grandmother's dish sets when she passes. It would be tempting for the nostalgia, but even my sister doesn't see the purpose in owning a hutch. Also, it's so incredibly sad, but I've been to three estate sales in the past year. At the first one, there were probabably five dining sets, why the f--- you would need five dining sets blows my mind, except of course that they were collectibles. All of them were sitting around, and I swung by on the second day. Nobody cares. They had $50 on the sets, I think, or less. Nobody cares. It was so sad seeing that house full of absolute junk, like that's what those people spent their lives doing. Their kids (much older than me, of course), were just trying to get rid of it all. I'd rather leave my kids a ton of stocks (as long as they know how to handle wealth), not some crappy collectible sets.
I also agree with the diamond rings. If they are worth so much, why are there so many of them in pawn shops? You basically have to sell at a loss, that is the cost of the pawn shop doing business. I would probably rank my high school class ring as worse, though. $400 and I didn't even think to put what I wanted on it, not that I even care now. What a ridiculous tradition, it only exists to make one company a ton of money, my parents really didn't have the cash at that time, and I regret pressuring them to get me one....