Retirement plans at the time of your grandfathers started in a good state: low unfunded liabilities, high population growth and lower life expectancy after reti

Retirement plans at the time of your grandfathers started in a good state: low unfunded liabilities, high population growth and lower life expectancy after retirement than today. Thus such plans were generous. In fact, they now seem way too generous: paying such obligations accumulated large unfunded financial liabilities (6 trillion is an estimate I saw a few times), which shows them as unsustainable. This means that the pensions of your grandfathers paid a lot of money of your children, so their parents (us) struggle to fix this. The solution is not more of the same defined benefit schemes to stick our children with still bigger bills. We must do something else (defined contribution? variable benefit?)