Not sure what's worse, losing things or forgetting you ever bought them. I bought some Indycals decals for a model car, never applied them to the car, forgot. Months later, thought "oh I need to buy decals for that car" and ordered a set. Then I got a nagging feeling in the back of my head. Sure enough, I now have two sets of the same decals!I bought some Indycal decals for a specific car I was building a few years ago and carefully put them in my decal folder, a few months later I wanted to apply them to the car and they had vanished without trace.
I bought a very nice condition Scalextric March 711 last year to use for a conversion, I put it in my storage boxes with all my other pending projects, a few months later I wanted to start the build and the car has disappeared without trace.
I know these have never been been moved from where I stored them so it's a complete mystery how they have disappeared.