In the movies, sometimes the world faces an existential threat, like for example in Armageddon.
And then the heroes figure out a way to save humanity from imminent extinction, sometimes at great personal sacrifice.
In real life, when we face an existential threat, the leaders of the world get together (at least those of them that can be arsed to turn up), and say "ah fuck it, let's not bother with this, let's just let the world burn".