They could have bought the sets, and overpaid of course then when they tried to sell them couldn't and just dumped them.
They are gold plated it's like 3 microns or something like that not even really weighable really. Someone probably got scammed into buying a few sets for $9.95, went to sell them and was told it's only worth 20 cents and just spent them instead in anger.
Could also be from the great American coin hunt and some dealer bought a collection with a few sets in it as part of a bigger whole deal and decided to set them free into the wild again since they really won't sell.