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This is one factor, but not the only one. There is also a reason for decreased fertility.

But, retirement is kind of like a lifelong ponzi, the last ones in support the top. It resets to some degree as the top dies though :D

It's the kind of Ponzi where there will always be suckers so long as there is life. :D

What a brilliant scam!

When life ends, there is no need for scams.