Debt is not the issue. It is the ability and confidence to pay it back that is of critical importance here. If You have a steady income of 100k, you can easily get a mortgage for 3x-5x your income. Your lenders are confident that you have the ability to keep your job, get salary raises or have assets to back it up.
Leveraging on debt is one of the marvels of the modern era, it enabled us to grow far beyond our usual constraints and capacity.
It was how the Europeans financed their continent wide wars, explorations and expeditions, garnering more resources and engendered higher and higher growth rates.
In America, the issue is we are now using the money we borrow for issues that do not push growth rates. We are essentially borrowing and giving it away to non productive causes with Obama's redistribution philosophy. Obama thinks we can do this indefinitely, he does not realize that he is squandering the goodwill and confidence of the United States brought about through a century of hard work and innovation by our forebears. He is eroding steadily but surely the power structure that drives this country.
Sooner or later, the lenders are going to say, wait a minute these guys are not actually going to pay us back, there is no growth no productivity. And when that happens, that's when SHTF.