Fool's Gold

Something that appears way more valuable than it actually is.

When Yosemite Sam and his contemporaries started mining for gold back in the 1840s, they’d often come across something that looked like gold, but was a lot less useful and a lot less valuable. This misleading mineral is called iron pyrite, but it became known as fool’s gold because of how many prospectors were fooled by its shiny exterior.

Today, the term isn’t only used to describe iron pyrite, but any investment or financial opportunity that looks (or ends up being) too good to be true.

Think: early internet bubble stocks that traded at 100 times revenue, and then...didn't.