Billions of years ago there was no multi-cellular life.
Trillions of years ago there was no universe.
And it just doesn’t matter how hot it was in the distant past. Our modern civilization with everything we now depend on (agriculture, technology and so on) was built in the last couple hundred to thousand years where the climate wasn’t all that different from the 1800’s. The issue is that it’s now changing too fast for us to adapt.
If you’re callous, you don’t have to give a fuck about the plants or the wildlife, fuck what’s “natural”, go ahead and kill all polar bears and pandas! But global warming is going to cause famines and disasters for us that will force billions of people to migrate north, which will trigger an upheaval of all societies and a global war that could turn nuclear. Because the systems we have in place now aren’t designed for a hotter climate, and the crops we have now can’t handle it.
How hot the dinosaurs had it doesn’t factor into it at all.