Well, maybe it's not so hidden, but here it is:
We live in a world with a global economy. This means nations are competing with one another for scarce resources. Some do very well and maintain a relatively rich lifestyle (like the USA). Some do very poorly (like Ethiopia).
There is a very real and well-known psychological drive which involves envy and greed, and which I'll call "keeping up with the Joneses." I do not think anyone would be surprised to think this happens on a national and international scale (i.e., people want their standard of living to be as good as anyone else's).
In theory, this means people in poor countries should have huge incentives to go to extreme measures to try to build wealth however they can, to catch up to rich countries. One way to gain advantage in this area is to be more exploitive of your particular natural resources, worry less about polution or climate change or things like that.
However, the destruction of planetary resources -- take, for example, the Amazonian rain forest -- does not just affect the long-term future of those particular nations, it affects everyone in all nations. Because the Earth is a single, interdependent biosphere. Which means those poor nations destroying their natural resources and polluting and otherwise harming the planet for some short-term economic gain (economic survival in some cases) are not just selling out their own future, but the future of the rich nations, too.
One obvious way to stop this absurd, global rat-race is to NOT have one nation be more economically successful than any other. So we find a way to give all economies, all societies, an economic equilibrium so there is no significant difference in standard of living from one place to another. Obviously, it would be imperfect, but if it is close enough, it should eliminate a major factor driving those willing to harm the environment for financial gain. People in rich nations would have to become less greedy and materialistic, the trade off being that their planet (and their descendants) might actually have a healthy future.
Yes, it is a simplistic view of the situation, but sometimes simple is good, in terms of a starting point. Well, I'm sure this only tracks what many others have to say, but perhaps the way it is stated is different. If not, then it's still one more voice in the wilderness adding to the call to action.