A common principle states that for many outcomes, roughly 80% of the consequences come from 20% of the causes. When applied to economics, this is often interpreted to mean that 20% of a country's population holds 80% of its total wealth. Critically evaluate the usefulness and potential limitations of this 80-20 principle as a precise model for describing wealth distribution in a modern economy. In your answer, consider factors that might cause real-world distributions to differ from this simple ratio.