Booms and busts repeat under new names.
“This time is different” rarely is.
It is January 2021. Everyone says this time is different. You have €10,000 in ten chips.
Every new era sounds certain at the top. The plain market kept going.
← Red LinesRed Line 30 of 48 The idea The numbers Where you see it Where it bends This game’s numbersHow strong the proof isBGood proof, with limits Where it comes from
Every boom comes with a reason why old rules no longer apply: a new technology, a new kind of loan, a new country. The prices then behave the old way.
In March 2000 the Nasdaq, an index of US tech shares, reached 5,048 on the promise of the internet. By October 2002 it was at 1,114: down 78%. The internet did change the world.
Tulips in the 1630s, railways in the 1840s, the internet in the 1990s, house prices in the 2000s: each time, “this time is different”.
Sometimes the world really changes. Ask for proof, not a story, and remember a good idea can still be a bad price.
Yahoo Finance, historical pricesdigrin, monthly price history (second check)
Eight centuries of data show crises repeating in the same shapes, but these are histories, not tests, and some changes really were new.
- This Time Is Different: Eight Centuries of Financial Folly Carmen M. Reinhart & Kenneth S. Rogoff, Princeton University Press, 2009
- Credit Booms Gone Bust: Monetary Policy, Leverage Cycles, and Financial Crises, 1870-2008 Moritz Schularick & Alan M. Taylor, American Economic Review 102(2), 1029-1061, 2012
Checked 2 Nov 2026 · How we grade
- A Strong proof: Many good studies or long official data, from different teams or countries, point the same way.
- B Good proof, with limits: Solid studies agree on the direction, but the size varies, or the data covers few places or few kinds of people.
- C Mixed proof: Some good studies for, some against, or the evidence covers only part of the line.
- D Thin proof: Mostly one book’s argument, one survey or stories. It may be wise, but it has not been tested well.
- = True by the sums: It follows from arithmetic, so no study can overturn it. We still show what real data says.
Carmen M. Reinhart & Kenneth S. Rogoff, This Time Is Different (2009). In our words, not quoted.
See it in numbers: Herding · Charts (From Zero)
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