Under Bush everything was made so Americans will go deep in debt. Mortgages were distributed to dead beats with no supervision, Credit cards companies got a green light to go ahead and screw people, the fiscal policy added to it, Americans were encouraged to shop till they dropped (a patriotic duty), etc, etc....

The result is that in 8 years of Bush the economy grew mostly by borrowing tons of money. Debts basically doubled at all levels of the economy: households, companies, and government. The overall debt grew much faster than it does now, even with Obama huge deficit, and this eventually caused the current crisis.

Of course the money was loaned by people who are the opposite of Americans: they have the humility and discipline to not spend even though they are much poorer. And their government has the discipline not to encourage short term spending spree (unlike Bush).

They are stupid however to invest in America. They have probably already lost more money than they gained through interests because of currency appreciation and they will probably lose a lot more. You can count on Americans to lose their money.