Yeah! Here comes the Magic Cupboard theory!
Debt is debt. Current projections have debt service taking the majority of our budget within a decade or so. Unless we're going to begin printing virtual money by the trillion, we have to radically cut our spending. If we do that, we're going to find it impossible to sell debt in dollars, so we're left with financing our own debt with made-up money via the fed. Already there's difficulty in selling longer term bonds in dollars. Eventually we'll have to pay for any imports with another currency. Then we'll be well and truly screwed.
All debt is most certainly not equal. Greece owed debt in Euros, a currency it does not print. Therefore it can in fact default on that debt. The US owes debt in dollars, a currency it prints. It is literally impossible for us to default on our debt unless we choose to. Since Greece has debt it can default on and the US has debt it cannot default on, the two are most certainly not equivalent.
If you believe the two to be equal, then by all means allow me to buy your house with a million Eskimospybucks instead of dollars. Debt is debt, so it's the same, right?
There are plenty of negative aspects to excessive US debt, so I have no idea why people need to invent wrong ones.