VanWinkle
Thinks s/he gets paid by the post
I see your point and agree that we must compare apples with apples. And we can do that, IMHO.
I am sure anybody with a financial calculator or computer can come up with the equivalent compounded return. I think the equivalent is about 5.75% compounded. Perhaps the financial wizards can confirm that, or show me the error of my ways.
The only reason the comparison should be apples to apples is that the argument is always that the person would take the SS early and invest it. They would allow it to compound and not take any money from the investment. I am not sure if this is reasonable, but it is the argument for reaching the "break even". In that situation, claiming that SS is an 8% return a year is disingenuous. It is done by many financial planners and educators.
The same could be said for the increase in SS benefits due to inflation (cola) that would affect the SS payout, and lessen the return on invested capital.