I suspect the reason many my age (or thereabouts) think 2000 was 'about 10 years ago' is because it's the last actual 'date' we all got genuinely worked about about
The build-up, anxiety, Y2K, conspiracies. It was the last 'date' that was a universal 'emotional' landmark
Some might argue this also applies to 9/11, but a) there was no 'build up' to that, and b) it was roughly the same time in our memories, so likely gets lumped in with 2000.
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So, the year 2000 looms large in all our memories because of the baggage around it, so our brain's perception of the passage of time will be warped by it. Like a weight on a rubber sheet; everything will tilt towards it, even when it 'shouldn't'
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