Economic model detached from reality
Government had failed to anticipate the scope and speed of the 2008 meltdown because their model of the economy was fantastically detached from reality.
In 2010 after the worst of the financial crisis had subsided but still soon enough for recollections to be vivid and hones, a group of Western central bankers and economists got together to assess what went wrong. To one participant in the meeting who was not a banker but had studied the nature of economies in great dept, this became strikingly and shockingly clear.