Not sure how your system works but US SS also covers spouses, widows, disabled workers etc which limit the average benefit.

Assuming full employment every year is a mistake. Also, 5% interest above inflation is an unpredictability good return, especially if you’re assuming it’s a safe investment. The stock market has mostly done well over the last century but start in 1969 and the 40 year return on the S&P 500 was 4.2% after inflation. Things could be far worse over the next 40 years, the 20 year S&P returns have been as low as 0.6% over inflation.

Running the numbers assuming zero taxes and fees is a separate issue.

There must be full employment every year with a mortgage. And I will work 6-7 years of my career just for this mandatory insurance. Sounds stupid and absurd when I read what I wrote. The widow might get something from that. But let me invest half of that in stocks and another half in 2 rental apartments and I will do much better that state. Plus it stays in the family after I die.

At an average of say 4% unemployment rate over your lifetime means the average person is unemployed ~1.6 years out of a 40 year working career. That’s not all in one chunk, but any time not spent working is time not funding a pension or retirement account.

In US SS your spouse can collect benefits when you died at 22 if you had a kid together, you also can collect benefits if your disabled. There’s obviously not 1.8 million in your retirement account to fund such things at 22. Similarly the payout for a married couple is 1.5x if only one of them have ever worked because it’s not a requirement account it’s a social security program, and then 75% if the worker dies. No idea how your system works, but it’s common worldwide for pension programs to do such things.