Irrelevant question - because the taxpayer hasn't held politicians feet to the fire to ensure the money was 'invested'. The voter is quite happy to have promises of wonderfully expensive medical benefits AND present day spending that is unsustainable.
You might as well postulate that the citizens OWE the victims of Bernie Madoff restitution for the money that Madoff stole. But the victims failed to perform 'due dilagence' and insure that the money was properly invested and wasn't a scam. Well - in the future, our kids/grandkids will likely tell us that we failed to perform the 'due dilagence' and we let the money get spent improperly on various scams, yet we kept re-electing the corrupt politicians, and the kids/grandkids will say that they are under no obligation to pay the bill.