“Bad money drives out the good.” This sentence is universally known as Gresham’s Law — named for Sir Thomas Gresham, who is famous for six words he never said and for a concept he did not invent. Over four centuries ago, however, Gresham did make the core point in a letter to Queen Elizabeth I: If government has minted both good coins (with lots of silver) and bad coins (with not as much silver), the public will hoard the good coins— driving them out of circulation.
Behn, Robert. "Simple Strategies Drive Out the Subtle." Bob Behn's Performance Leadership Report. October 2009.