Oh really? And just what would the earthbound do for economic activity? flip burgers, shuffle paper, sue each other, and walk each other's dogs? Heavy industry will never cease on Earth. It just won't pay to manufacture all the components for heavy and military equipment in LEO and try to ship it down. This is an enviro-whacko pipe dream.
The present economic theory says that their are infinite wants and limited means. If we mine the asteroids, settle the planets and move out to the stars we will have the whole universe at our feet. Infinite wants and infite means! Its a win win.
Its not an environmental wacko idea to want a better living place. We can do better.