Eight years ago, we were in the midst of a frothy, frothy tech bubble.

It was all anyone could talk about--at investor conferences, in the pages of The New York Times and The Wall Street Journal, in notes by research analysts. "Irrational exuberance has returned to the internet world," The Economist warned, in one of many stories on the topic. That late-1990s feeling was "back," said Esquire, pooh-poohing LinkedIn's business model and arguing that "American ingenuity and American gullibility" were thriving in Silicon Valley. This magazine was not immune to writing about it, nor was yours truly.

Then, poof! It was gone. The tech bubble did not burst. It simply disappeared as a matter of concern. Investors kept on investing. Valuations kept on rising and falling. Companies went public, got acquired, succeeded, and fell apart.