“Every once in a while, an up-or-down-leg goes on for a long time and/or to a great extreme and people start to say "this time it's different." They cite the changes in geopolitics, institutions, technology or behaviour that have rendered the "old rules" obsolete. They make investment decisions that extrapolate the recent trend. And then it turns out that the old rules still apply and the cycle resumes. In the end, trees don't grow to the sky, and few things go to zero.”