It's like saying you wake up every day and "worry a great deal" about a 10.0 earthquake and 200-foot tsunami wiping Portland off the map while a satellite falls from space and lands on your head. A lot of people think we're either doomed already, or somehow politicians will somehow work with scientists to somehow pull a last second miracle out of their asses. But either way, it's not something we can prevent individually, so why worry about it.
(Not necessarily saying this is how I feel. But you asked for theories, and I think this is the most likely.)
(Not necessarily saying this is how I feel. But you asked for theories, and I think this is the most likely.)