The only thing more dangerous than an economist is an amateur economist

--- ascribed to Hal Varian by Ludwig Siegele in "The story of the internet is all about layers" in The Economist's June 2018 Special Report "Fixing the Internet."

However, The Big Apple cites it as "Bentley’s Second Law of Economics" in an entry from July 30, 2010, suggesting that it has been cited in print since at least 2002. It also observes,

“Bentley’s second law” has been accompanied by another law since at least 2002: “Berta’s Fundamental Law of Economic Rents: The only thing more dangerous than an amateur economist is a professional economist.”