The case of Bernard Madoff, sentenced to 150 years in prison on Monday, is proof that it takes a village to keep a $65bn fraud scheme going.

Ordinarily, Ponzi schemes like Mr Madoff’s collapse of their own weight within a couple of years because it simply becomes too difficult to pull in enough new money to pay off earlier investors. The recent lengthy boom cycle created unusually fertile conditions for deceit, spawning a wave of frauds. Good times meant fewer investors asked for their money back and the rapid growth of complicated investment products that no one understood made high apparent returns such as Mr Madoff’s seem less implausible.