It was precipitated by the virus, and made worse by the crazed decisions of governments around the world to shut down business and travel. But it was caused by economic fragility.

The supposed greatest economy in US history actually was a walking sick man, made comfortable with painkillers, and looking far better than he felt—yet ultimately fragile and infirm. The coronavirus pandemic simply exposed the underlying sickness of the US economy. If anything, the crash was overdue. 

Too much debt, too much malinvestment, and too little honest pricing of assets and interest rates made America uniquely vulnerable to economic contagion. Most of this vulnerability can be laid at the feet of central bankers at the Federal Reserve, and we will pay a terrible price for it in the coming years.