until you find out that beanie babies weren't irrational either
there was a supply crunch with the manufacturer in China, it was rational to think it wouldn't be solved, creating a limited supply item that had more demand than the supply. the founder solved the issue and flooded the market with beanie babies, prices crashed at that point
As (probably) the world's largest reseller of Beanies at the time, this was 100% nothing to do with a Chinese supply crunch, as far as I was ever aware.
It was 100% to do with Ty corp's very clever handling of distribution, limiting where, who and how many Beanies could be sold.
There was a huge over-supply of the less rare Beanies and a huge under-production of the rarer ones. All done on purpose.