I'm much more fatalistic for humans than either of you. We've been downright nasty to all other forms of life on this planet for millenia, and now we've stepped up from just being nasty to being positively ecocidal, ratcheting up the biodiversity loss with each new techno-monstrosity we create. We are 100% headed for the trash heap, IMHO.
You're right that we are "thinking animals", but we've got a global animus now that is obsessed money and growth. We're infected with a greed virus that I think is fatal to its host.
And the problem, as I see it, and alluded to in my OP, is that local incentives are all wrong now. Nearly every decision that is rewarded by the markets at a local level is bad in the long term. You can teach a small fraction of people so that they may become enlightened, but greed spreads faster, and is better rewarded. In a game-theoretic view of this, it will always pay to defect from those conserving and living sustainably, as you externalize the losses onto an unseen and uncared-for future, and spread that loss among everyone else. Moral hazard, everywhere. But now, with global civilization and industrialization, and instant communication, we've become more than a diseased troop of chimps headed for a brawl in the forest; we're an insanely overpowerful superorganism driven by unquenchable lust for exponential growth and armed with millions of years of energy reserves--even nuclear weapons! There's literally nowhere on Earth that we can't or won't go in search of resources or vacation potential.
As much of an atheist as I am, I can't help but feel a pang of spirituality about this, and that pang is, unfortunately, despair for the inhabitants of this green jewel that is being ravaged. And by inhabitants, I'm broad in including all living things, regardless if they are cute or have fangs and spit venom. All those funny animals, frogs, plants, fungi. They got fucked because money.