[duncanr]

Would you be happier to say that the utilisation of raw materials 'tends towards' a zero-sum game, then? ;-)

I don't disagree with what you say (although I would argue the likelihood of this theory playing out in practice and over the long term seems low), however this is largely irrelevant to my original point which was that many people who aren't successful (by some measure) will complain that inequities 'in the system' are unfair, and much discussion will ensue because of that.