Because we're idiots and terrible at forward planning. Currently pensions and retirement ages are based on the idea that there will be some large cohort of peop

Because we're idiots and terrible at forward planning. Currently pensions and retirement ages are based on the idea that there will be some large cohort of people working to pay the pensions of the folks that are retired. In fact, governments are even borrowing against future pension contributions made by that cohort, so it's not even that the future cohort needs to pay for the current cohort, they need to cover it and some to make up for the lending. Realistically, this is never going to happen, and this is where fiscal policy starts to deviate from mathematical first principles. In case there is some kind of reduction in the workforce, then we do not have a plan to care for our elderly. Already, young adults are finding it difficult to afford homes for themselves, even with a higher proportion of families with two incomes. We would see an increase in the chasm between the rich and poor, as those able to own property would be able to both look after themselves and their families, and would be able to continue to grow their wealth by charging rent to those who are unable to afford to buy. This especially would be accentuated if population decline were gradual, as then the rich would be able to continue to snap up the homes that come onto the market and rent them out. A short sharp halving of the population would likely leave a surplus of homes on the market, at affordable prices for everyone, and would perhaps even lead to a better quality of life for most. But that's not an organic process, and certainly leads to a worse quality of life for the unlucky half...