Wouldn’t be able to have clean fresh water to drink and could get sick without it humans wouldn’t be able to stay warm without heat and indoor plumbing would allow a sanitary place to relive bodily functions
Bonds are considered very low risk for the very simple reason that they are backed by the power of the credit of the United States.
So, the only REAL risk for investors is that the United States default on its debts, that is, that they don't pay their debts. This could happen if all foreign owned debts are called in at once.
