Watches

*gamble

It worked out well for clymer and Mayer

I think this can sometimes be true to the extent that you treat them like one, but often, folks are looking for a watch to wear and they're hoping they'll also get a good return which is rarely the case. If you're wearing the watch, you'll likely want/need to pay insurance on it, depressing your returns. Not to mention, scratches and dings cause the watch's value to depreciate.

Also, regardless of whether you wear it or keep the watch in a safe, unless you're a well-established watch dealer, you're going to have to give up a ton of your upside either to some trusted middleman or by needing to discount the watch when selling it to a party who can't necessarily trust the sale on their own out the gate (compare prices on r/Watchexchange vs on Bob's watches or Hodinkee).