The government borrowed it and then took it out and spent it on prostitutes in Columbia (for one thing), and various other things ~ but it was a dedicated tax and the initial obligations remain ~ it must be spent on payments, or it must be refunded. You simply cannot write it off the books ~ or else!
Apparently you are completely stupid on multiple subjects.
The government "borrowed" the money from itself and has spent the money. It is gone. Whatever the hand-waving involved, the money is gone.
Future Social Security and Medicare benefits will be paid with money taken from future private sector workers and investors.
Period.
This is reality. All the rest is just bluster.
If you think there is some moral debt that future workers owe to those who came before them and ran up a $16T national debt, I'd love to hear you explain in straightforward term why that is.
Actually the USSC has ruled that the government can change the rules on payments any time they want to, so a refund does not have to be paid.