A hedge fund manager who made what is thought to be one of the biggest percentage profits of all time bowed out of the business on Friday with a fierce attack on the “idiots” running big banks who were willing to take the other side of his bets.

Andrew Lahde, founder of California’s Lahde Capital, used his farewell letter to investors to round on the US “aristocracy” able to pay for their children to gain a top-class education.