Who said anything about preordained?
As player*: was in a party that failed to save the world, directly leading to a cataclysm that killed many millions and ended the campaign (1991)
As DM: ended a campaign by running a break-the-world-to-save-the-world story arc, the PCs didn't know about the break-the-world part until the very end (1994)
As player*: was in a party that, while maybe not breaking the world, certainly changed it for everyone and ruined it for many by, in-character, causing the world to change on the fly from the 3.0 rule-set to 3.5 (2007)
As player: was in a party that, while saving/fixing the world, sank most of a continent and part of another, again killing many millions (2018)
As DM: in my current campaign a party actually broke the world years ago (both in real time and game time) without really realizing what they'd done; other parties (and some powerful NPCs) are only just now starting to clue in that something's going wrong in a very big way. Jury's very much out on whether anyone will (or can!) try to fix it, or if it's already too late; in either case I can mine this for plot ideas for some years yet.
* - and as fate would have it, in both these cases it was my at-the-time character who tipped the balance; even weirder is that the 2007 character was my attempt to re-make the 1991 1e character using 3e rules, so in effect it was kinda the same character both times.
