scary quote. why did he say it was inevitable?

According to this widget: http://www.usdebtclock.org/ US government has roughly $2 trillion in revenue and interest on the debt is 6.6%.

According to this graphic: http://en.wikipedia.org/wiki/File:USDebt.png Government debt is $7.5 trillion. At 6.6% interest, interest payable by government per year is roughly half a trillion dollars. That is 25% of the government budget.

25% is huge, but not huge enough that would lead to a collapse just yet. A $60,000 income individual paying off a mortgage of $200,000 pays just over $13,200 in interest a year, which is roughly 22%.... If you take account of taxes, with an after tax income of roughly $45,000, the ratio goes up to 29%.

I suspect the government will have to rack up twice as much debt before people begin to suspect its ability to pay it off (50%). i.e I wager the US has as at least much time as it takes for the government to double its debt to tax collected ratio. How long will that be? Now that's a question to ask.