It happens in all aspects of collecting... I had 30,000 pieces of sheet music from my fathers estate. I could not get but a dollar or two on ebay per sheet and seldom sold any. So I thought I would sell in bulk to a person back east at 80 cents each. That person then put the sheet music on ebay and got anywhere from 10 dollars to several hundred dollars for "my sheet music", talk about depressing!
Finally I thought I would make another run at it and right back to the same problem...can't sell it!

I finally figured out that if you search for "sheet music" it pulls up 10 to 20 thousand sheets listed at any time of day. So the bottom line is he had a following and I did not! Most people are only able to search a few pages at a time before they get rummy. The same is often true in chip collecting.