The Great Beany Baby Bubble is a fascinating book, that outlines the mentality boomers had about collecting things like baseball cards and the circumstances that led to it. Basically, Boomers grew up watching a few select examples of ephemera from their own childhoods (like baseball cards and comic books) become incredibly valuable, and so when they had kids of their own they made a big deal about storing baseball cards in perfect condition, assuming one day some might become valuable too, thus flooding the market with pristine baseball cards nobody cares about. Meanwhile, they were determined to throw in the trash all the stuff their kids actually cared about that would someday increase in value, because people eventually want to collect the stuff they cared about, not the stuff their parents thought they should care about.