Paying just the interest on the debt takes a significant portion of government revenue, although I don't have citations handy. As that proportion increases (th

Paying just the interest on the debt takes a significant portion of government revenue, although I don't have citations handy. As that proportion increases (that is, how much of government revenue is spent just on paying for past debt, rather than anything productive), the likelihood of some threshold being crossed increases. But until that point, the government is able to sweep it all under the rug.