Gresham

Gresham’s Law is an economic principle stating that "bad money drives out good." When two forms of currency are accepted as equal in value, people tend to spend the lower-quality or less valuable money while hoarding the more valuable one. Over time, the less valuable coins circulate more freely, and the higher-quality coins disappear from everyday use. This effect occurs because individuals act in their own best interest, and the law reflects how different types of money coexist in markets, often leading to the deterioration or disappearance of higher-quality currency if the monetary system isn't carefully managed.