A lot of this comes from extensive travel and spending time in the third and second world. Many of the poorest billion simply do not realize that it is against their interest not to, for example, dump chemicals and trash in water they drink from and bathe in. Or just simply that littering is a problem. To be clear I'm not faulting them, like everyone else they are mostly good people and if they had better access to information I have no doubt they'd act differently but there is a huge need to educate people that is not being met.
It's also just hard to imagine consumption of everyday objects at the global scale.
But it's really hard to feel like recycling one more bottle is going to save the world when you've seen dump trucks waiting in line to dump industrial waste in rivers. But this sort of thing is likely happening every day, repeatedly, in many places around the world.
I once drove through a section of highway in north western Peru that was just an open air landfill on both sides, maybe 5 feet tall on average, continously for an hour. It's just hard to imagine that stuff like this exists if you've never been exposed to it.
And that doesn't even match things I've seen only in documentaries like https://m.youtube.com/watch?v=dd_ZttK3PuM
I believe that our problems are technically still fixable but that the coordination necessary is, if not totally infeasible, far beyond our current willpower to achieve.
The rich (and all but the poorest Americans are rich for this discussion) will basically be fine maybe minus inconveniences for the near future.
But I think things are going to get drastically worse for many people over the next 50 years.