Because economic performance does not account for unsustainable consumption of natural resources as a cost. Say I have $1M in the bank with a $10K monthly income. I am spending $100K per month. What is wrong with me measuring my happiness by the amount of money I spend?
Economic performance is a number. You can optimise it. Or you can choose any other number, and optimise it too. Is money the best number? Why not median lifespan? Why not reported happiness? Why not median wealth? US has much more money than EU, but the cost is the streets are covered with homeless. Is US really more prosperous if it can't provide a decent life for the equal percentage of people compared to EU countries?
Economic performance is a number. You can optimise it. Or you can choose any other number, and optimise it too. Is money the best number? Why not median lifespan? Why not reported happiness? Why not median wealth? US has much more money than EU, but the cost is the streets are covered with homeless. Is US really more prosperous if it can't provide a decent life for the equal percentage of people compared to EU countries?