It's pretty logical why people over history want to believe the world/society/civilization is ending - it makes a superb excuse for extremely localized personal choices and values.
Societies and civilizations always end. That's what they do.
Nobody said the world is ending. The claim is that it's about to get extremely inconvenient for humans.
It's pretty logical why people move the goalposts — so they don't have to actually do anything to change.