Because humans are inherently selfish.

Are rich countries like US/EU etc. going to just allow tens/hundreds of millions of Africans to immigrate into their country when large parts of their continent become uninhabitable ?

Or are we going to quietly just let them die like is happening now.

Rich countries are also sitting idly by while large numbers of Africans starve to death due to energy shortages. The Africans are going to come out worse whatever happens as long as they look to the US/EU to fix their problems out rather than sorting out their local economy.

If they could manage the sort of wealth generation seen in China or India, they probably could make it through any amount of climate change due to having lots of cheap energy.

Some of us will, and it'll suck for the rest. You know evolution is made of dying, right?

> You know evolution is made of dying, right?

Not true in the slightest; evolution is solely driven by differential reproduction rates. You'll see evolutionary dynamics even if every organism you study is immortal and invulnerable.

Dying is just one of many things that affect your ability to reproduce.

In theory, sure. But in practice, it's driven by dying.

No, that's still not true.