Let me start by saying no one knows what would happen if the US defaulted on its obligations.
Bruce Bartlett, a guy who knows a lot more than me was interviewed a while ago here:
http://www.salon.com/technology/how_the_world_works/2011/01/05/bruce_bartlett_on_tea_party_monumental_insanityAnd explains a lot of why this is extraordinarily dangerous and you should read it if you think a default is no big deal.
That said, here’s my take of the worst-case outcome, which is more extreme: US debt is considered zero risk, and a lot of people and organizations hold it throughout the world. The sum of US obligations is multiple orders of magnitude larger than Lehman Brothers. Lehman Brothers’ default and the chaos that ensued nearly ended the world as we know it.
If you don’t believe that and you think Lehman was no big deal, then sure, maybe you can believe a gov’t default doesn’t mean anything. Maybe you can compartmentalize default into talk about credit ratings. RJ, the credit rating for a bond in default is D. As in Default, or Done, or Dead. If you’re a D, you don’t have a credit rating, you can't float a bond at any interest rate, you're done. But worry about a credit rating is a tiny concern.
So if the US defaults, what about your money market account? Most of ‘em hold short-term gov’t paper, or t-bills. If the gov’t is in default, you can’t get money out of your money market. It not only breaks the buck, it goes to zero, until the default is cured. What do you care? You don’t have money in market accounts. Well then how about the people you do business with, or your bank, or your landlord, your employer, or your grocery store, or your pension fund? A US gov’t default will put the liquidity of our system to nearly zero. Without liquidity, the economy stops, dead.
Hell, I’ll go even further. Why does a dollar have value?
Old timers know I’m certainly not a hard money advocate, and consider a dollar to be worth something because other people think it’s worth something and will give things and labor for it. But what happens to the value of the dollar if the gov’t defaults? Well, we might actually prove that Pigmaila and TheodoreLogan were right in their belief that metals were the only way to preserve wealth.
Because if the gov’t defaults, and liquidity goes to zero and the economy goes to zero, which will pretty much mean the dollar goes to zero, and life as we know it will end. That’s contagion in a highly interconnected financial world, and I can’t fathom why anyone would consider this possible outcome a reasonable gamble for any return.