You see this often, but it makes sense
Our brains don't measure time in a purely quantitative way. It's more qualitative
Meaning: We tend defer to events, 'landmarks', i.e. "It's been a while since [significant event]", rather than "It's been 56.3 days since new year"
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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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