Traders realized Mr. Bessent’s efforts were too puny to counteract the Titanic forces pushing rates up: elevated inflation; unsustainable government deficits; private firms issuing tons of debt to finance A.I. Then there is the greater risk associated with U.S. debt in general, because investors worry the United States is being run by what might politely be termed the B team — that is, people who may not take seriously their responsibility to safeguard the full faith and credit of the United States.