—Michio Kaku. "Will Mankind Destroy Itself?", 2010
Sadly, you've also described an increasing number of western political conservatives.
https://m.mic.com/articles/95234/psychologists-discover-the-...
As far as nuclear bombs, we don't really seem to be using them much anymore. They are just trump cards in the mutual assured destruction game.
On the contrary, I think 'we' (the US) use them every day as leverage and a deterrent. We just don't need to detonate them anymore. I think there is more to it than them being just a trump card. You only get to use a trump card once.
For the few entities with nuclear weapons, it's MAD. We would only play the card once, since it would be the final round of the game with that entity.
Somebody could come up with something tomorrow. Maybe a bacteria that can populate the ocean, which precipitates carbon from CO2 in the air, and drops little pellets to the bottom. Probably not a real practical solution, or even a good idea, but it shows how things could rapidly change if the right tech comes along. They wouldn't need to get everyone together - just a petri dish thrown into the ocean.
We are still thinking of solving today's problems with today's technology, which I agree is futile to get everyone on the same page.
So any intelligent life-form would have to survive this period where they have the technical intelligence to create damaging things such as cars, coal-fired power plants, nuclear bombs, etc but lack the maturity and will to manage the bad issues resulting from that technology.
And I can't see how we will create the solutions on a global scale within such a divisive world society. It just won't happen. And any life-form would go thru the same phase. So life will flourish until technology enters the picture, and then the issues of technology (pollution, over-population, resource depletion, etc.) will happen very quickly and destructively since any life-form would be emotionally ill-equipped to handle them. I mean, how can we construct global solutions when the majority of people still believe in a 'god'. We are still immature apes yet with nuclear bombs.
It would be a rare civilisation that would be able to survive this period. And hence that's why intelligent life-forms would continually rise and fall, but never progressing past a certain level of intelligence.