Nobody has yet mentioned the Elephant in the Room.
Pensions worked, for the State, back in the 1950's when people had a ton of kids. People worked to age 65, retired, and then died one or two years later. Many didnt even make it to 65. Housing was cheap cos a) couples stayed together and she was a home-maker , not a career women and b) Social Welfare did not function to inflate house prices. On average, one pensioner was supported by 16 earners in employment and paying their taxes. People often inherited a home while young enough to start a family themselves. Many people commenced employment at age 16 and continued thereafter. A taxpaying employed man offered a much better prospect to women, for reproduction, than a long-term unemployed loser. The vast majority of kids were born to married women with a working father. The dole was seen as undesirable and best avoided. Thus a taxpaying-nation begot more of the same.
Today. The opposite to most of these. The West turning into a gigantic retirement-home...with many young people born into ghettos.....not financially nor economically sustainable. London (and Silicon Valley) is increasingly for the twenty-somethings who work but dont have kids - wealthy and barren. Like the Fall of Rome..........it plays out in the financial markets before it hits people on the streets.
the UK was the first country to Industrialise and may now be the first to experience a Post-Industrial collapse. Pensions and everything else all gone down the swanney.