Whether we are talking of the Golden Rule, the ethical precepts of the Quran, the eightfold path of Hinayana Buddhism, or Kant's Categorical Imperative, we can't get off the moral hook by saying that our moral behavior, if no one else followed it, won't save the world. We just can't. But that's what we are trying to do environmentally. Because we are biologically and culturally programmed to behave in exactly this way. Biologically we are a species which evolved to adapt quickly and rapidly to changing environments and conditions by exploiting them in a vast diversity of ways.
Botanists define weeds as plants of disturbed ground.
By that standard we are the preeminent weed species in the world - only unlike other weeds, we make our own disturbed ground. We are the inheritors of the western tradition of technological and opportunistic triumphalism. But exploiting opportunity often means, quite specifically, ignoring the full impact of what we are doing. We are simply not prepared to take into account the distant secondary and tertiary consequences of our actions, of that very exploitive temperament that marks us as human. It's not that we can't learn to value the environment, and to seek to behave morally on the basis of that learning.