It's a gamble on the Stock market value at the time you retire. The Stock market can reset and recover every ten years. A retiree can't. I remember people that retired in 2007 were screwed when they lost 60% of their retirement.
"You can top up individually if you want to, but the basis pension should be risk sharing between people of various ages."
This is what we have : basis defined benefit pension with risk sharing among generations called "Social Security" and "top up individually" in form of IRA/401k etc.
"because their pensions were 401(k)s. These are individualized pensions with high fees. People don’t understand the risks they take, they do not share risks over generations."
The typical number when these things first started replacing defined benefit pensions in the early 90's were maybe four--to the average employee who knows nothing about investments vs. pension fund managers who work in it every day of their lives it was like all of a sudden handing a scalpel to a person who needed heart surgery and telling them to do it themselves. The company would always say now it's your responsibility to make good choices and blah blah blah. The risk was all on the employee. Sure, the stock market may ultimately win over a 40 or 50 year period, but most retirements are a 15-20 year window where the person is at the mercy of the market. A person retiring in 1967 would be out of luck during the inflation and stock market carnage of the 1970's. They would be in their 80's by the time there was a turnaround. I've heard the number 40% of what securities lost between about 1968 and 1983.
I remember people that retired in 2007 were screwed when they lost 60% of their retirement
If they had invested in divided paying stocks, they would have been OK. That, and you shouldn't retire without at least $500,000 in cash to ride out any downturn.
https://www.bloomberg.com/view/articles/2017-12-28/what-makes-the-u-s-retirement-system-a-bad-example