In order to stay prosperous (and world reserve currency) under such debt the USA must take on more debt that is owned by foreigners. I know it makes no sense but its no different than if you owe the bank $10,000 they own you, but if you owe the bank $10,000,000,000 you own them. The USA owes many nations money but those nations do not want that money to become 0 so they service more debt to America. Eventually all currencies fall to 0 but it is bad politics to be the one in charge when that happens. The debt will continue to pile on until people trade in something other than the USD. A heavy military and debt keep America relevant. Other than that what do they have to offer that isnt in silicone valley?