How likely is another plague, another world war? Is this a case of confirmation bias or are we just 'flawed' in such a way that we overcompensate for progress. I'm referring to how progress (e.g vaccination, societal tolerance for differences) is very easily reverted.
It isn't. If you see a case where you think history repeats, you haven't looked closely enough at the details. Certain types of events (war, plague) repeat, but they are only ever similar in the broadest strokes. The human brain does love to find patterns, though, even where none exist.