During the 3 year pause in payments, they took on new debts:

But many borrowers also took out additional debt. According to TransUnion, about 53% of consumers with student loans increased bank credit card debt, 36% took out new auto loans, and 15% added mortgages and unsecured personal loans. As long as borrowers didn’t have to repay their student loans, they could afford to make payments on other debt.

The Student Loan ‘Payment Shock’ – WSJ

Personal financial literacy is said to be very low in the U.S.

Coldstreams