A guy with 100k income and 90k debt will be able to allocate that portion of his income necessary to pay off his debt in a reasonable time (10 years?) But how is he going to do it? By either making personal spending decisions to allocate more income to paying off the debt, or grow his way out of his debt by raising his income so that his debt payments represent are a smaller percentage of income. Our government can't do either.
Spending wise, what is congress going to cut? If it's an individual with debt, there's lots of things to cut: drive a less expensive car, live in a cheaper apartment, go out less, stop tithing, stop giving to charity, pick up a second job, borrow interest free from a relative to pay off interest-bearing debt, etc. Individual debt is so much easier to pay off because it's a single person making individual choices. Also, there's bankruptcy if it came down to it. Sure there would be the stigma of being a bankrupt and a hit on the credit score, but that would be after a single person weighs the options and chooses the most personally preferential way to pay off the debt.
What can our gov't do to pay off our debt? Raise taxes, which would impede future growth, cut spending, which is politically unfeasible (at least to the extent necessary to pay off the debt), inflate our way out (which will hurt both individuals with assets as well as future investment), or sell off assets (what are we really going to sell? Apart from federal lands which might garner a trillion). Raise taxes and 50% of voters are against it (ignoring whatever economic effect). And what can be cut? Military? Probably but there are political consequences to that. Medicare and SS? Sure, it could be cut, but again with severe political repercussions. Homeland Security? Education? Dept. of the interior? FAA? FDA? FCA? What can realistically be cut to apply to our debt? A single individual would quickly decide what to cut based on individual preferences, but our political system cannot act as an individual.
A recent grad that grows his way out of debt is able to do so precisely because he doesn't have high overhead coming out of school. I have a friend who is 150k in debt, but his salary is 150k a year. He's able to pay off his debt because his non-debt expenditures are going to be far less than that salary. But with our gov't, there's no politically feasible way to pay off that debt. We're spending more than we're taking in, unlike a recent grad, or a person with 100k income and 90k debt. We're taking in 150k a year and spending 200k, without the ability to make the personal choices necessary to service that debt. That's the problem. And of course everyone has their own answers. If it was me I would lay a 10% cut in spending across the board, political consequences be damned, but I'm not in washington, and I don't have to worry about being re-elected or politicking to get my personal preferences enacted. And, there is no bankruptcy option for our gov't. Sure, the EU can bail out Greece, and the US if needed could even bail out CA or NY, but at some point it all has to be paid or the crap hits the fan.