In theory at least, the dollar is backed but all the goods services and products built by Americans. The debt, so long as it increases greater then the increase in production, is a danger and will decrease the value of the dollar relative to physical products gold, silver food, oil etcetera; IE it is inflationary, at this point likely hyper inflationary. How though is bitcoin or any other crypto currency any better when they are literally nothing but digits on a computer whose value is based on pure speculation?
