They believe that the value of the additional 'investment' would exceed social costs of the additional pollution. They have made a grave error. These economists have overlooked that any investment directed by the market toward cutting pollution is actually contributing to human welfare by conforming more closely to consumer preferences. However, even though there is no such thing as a free lunch the free market will still let us eat our cake and have it too. Economic growth is the answer.
Economic growth is actually a resource generating process.
It is economic growth that has flooded the Western world, and even parts of Asia, with unparalleled abundance. That is why only rich countries have the resources and the incentives to clean up the environment. The reverse, of course, is equally true.