Has nobody noticed? There was no "debt" to begin with... it's the same situation if you owe your neighbor $100 and he owes you $100 - it balances out so neither of you owe anything. Adding more people to the "loop" doesn't change the net equation, and the arrival of the tourist with his $100 is purely incidental and has no net effect on the situation. The national debt, on rhe otherhand...