Perhaps beanie babies is an example that we actually know about.

I wonder if there are more recent examples?

NFTs

I think NFTs were this niche thing only crypto people were dealing. It was not a wide cultural phenomenon. I bet the majority of the population don't know what it is.

I'm not sure if I'd call it culture wide, but a significant number of non-tech people in my life were not just aware of it but actively considering "investing".

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.