My novel MagicLand is tangentially related to this. It takes place 2,000 years in the future. In that future, the wealthy solved the problem of climate change by simply eliminating the vast majority of the population. They also augmented themselves in a way that helped them adapt.
We might scoff at such ideas, but history demonstrates what humans are capable of doing. Whoever can afford the great technologies medicine will offer to extend life (for example) will do so. If it is convenient to simply do away with the rest of humanity, I can see it happening. That is not the same as suggesting such a thing is likely. A possibility is not the same as a likelihood. But underestimate the ultra wealthy class at your own risk, as you so well point out.
Luckily the novel itself is not about despair. I think, in fact, we live in a time where we could use fewer anti-heroes in our fictional worlds and more heroes. Precisely because heroes are the exception.
Thanks for the sad reminder of where we are in Ayn Rand’s world.