Most of us remember the exuberance of the stock markets at the height of the dotcom bubble. Much, however, has apparently been forgotten. Then, back in 2000, internet companies that were planning to sell door knobs (but hadn’t sold one yet) were given a valuation that wouldn’t even be justified if they sold all door knobs in the world, let alone the ones bought over the internet. Their business models were weak, their revenues non-existent. Prices departed from value to a degree investors hadn’t experienced before.