Also, working until age 70 allowed me to replace a few zero's and a few low wage college summer job years in my 35 year average. It was a double win that way.
Furthermore, as someone who has been saving for retirement his whole life the age 70 1/2 minimum IRA and 401k distributions will kick in at about the same time.
That is another source of age 70+ income. If you can wait to age 70 to collect social security (and many folks can't afford to) then you get some substantial benefits. Plus if (or should I say when) you die, your wife gets the larger of her or your social security. If you are a typical breadwinner with a larger salary and your wife took a few years out of the work force to raise your children, then maximizing your social security by working until 70 will give her a larger income when you die, if she out lives you.
The only down side is that the more income you have the higher the taxes on social security and the higher the medicare payments, but even though your “taxes” are higher, so is your income after taxes.
And yes, I lucked out and was able to do the file and suspend thing with my wife. She continued to work and was able to draw my 1/2 full retirement age social security on top of her salary.
You need to study the options, figure out what you can afford to do and then maximize your social security benefits.
“... there is no other absolute way to get a confirmed 8% per year increase in any investment for working from full retirement age until age 70.”
That 8% per year includes average mortality risk, so I wouldn’t quite call it “confirmed”.