"Collapse" is maybe hyperbole in this case, if it's building on our own history to extrapolate forward. For us, certain societies have collapsed, and with them have been lost certain practices or technologies, but human civilization as a whole has been largely steady or growing since the agricultural revolution (using population size as a heuristic). There's always the threat of ecological collapse, but that's something that has only happened a few times in the history of life on the planet, and we haven't really faced anything like it before at civilization-wide scale. There's always been another group to move in and take up the abandoned land. Without some major technological breakthroughs, yes, we're likely to face a collapse eventually, but as a biosphere, not merely a civilization. Short of that, people seem to keep on keeping on.
I think the mistake comes from something common to a lot of sci-fi, which is mistaking the scale of a planetary setting. It takes a lot of energy to disrupt life on a global scale (we're managing it, but it's taken hundreds of years). "At some point" is carrying a lot of weight in that observation.
> "Collapse" is maybe hyperbole in this case, if it's building on our own history to extrapolate forward.
In the story, "at some point" generally involved technologies we are currently incapable of; the greater technology actually facilitating the greater collapse. Which at the most obvious included nuclear catastrophe.
I think my contention is with "collapse" rather than something like "crash". The latter implies a cyclical downswing (reasonable), the former implies the absolute end of a cycle through the non-viability of the prior order. One means "start the round/match over," one means "find some wood to start carving a new board and game pieces". The new game probably won't be recognizable, and you're talking about not just the events but the setting and context being unfamiliar. Every civilization goes through that? I suppose, but only because every life-bearing planet goes through that, civilization-bearing or not.
> always been another group to move in and take up the abandoned land
Completely agree with your points, but I think itβs worth mentioning that the collapsing populations may not have been aware of this depending on their level of isolation and cultural view on outsiders.
I think the mistake comes from something common to a lot of sci-fi, which is mistaking the scale of a planetary setting. It takes a lot of energy to disrupt life on a global scale (we're managing it, but it's taken hundreds of years). "At some point" is carrying a lot of weight in that observation.