> I thought the idea of Social Security was an insurance program to guard against you outliving your means if you live long enough, not an I-get-paid-back cash-out of your payments. Is that a fundamental misunderstanding about what the purpose of SS is?

Yes, this is a fundamental misunderstanding of social security. Social security isn't insurance or an investment, it's a tax that's presented as an insurance or investment in order to make it more palatable. The social security tax rates were set with the demographics and life expectancies in mind decades ago. And now that these demographics and life expectancies have changed we'll either have to drastically increase the tax workers are paying, or drastically cut the amount that people withdraw.