via Bloomberg:
The Bloomberg analysis found that loans issued about six years ago have the highest cumulative loss percentage compared to any other year since the financial crisis ended. This indicates that students who took a loan in 2012 have had a much more difficult time making their monthly payments compared to students who received loans shortly before and after — students who have had a similar amount of time to pay them down.
A large percentage of those who took out loans in 2012 are currently 24-33 years old, an age where many are generally establishing themselves in their careers. Borrowers in this group entered the labor force when the unemployment rate was twice as high as today and may have found it difficult to find a career track in their desired field. Further adding to the difficulties faced by this group was that finding a position in 2012 took almost three times longer than today, according to data from the Bureau of Labor Statistics.
Borrowers in the 25-34 age group owed $489 billion as of the third quarter, slightly less than $530 billion balance for 35 to 49-year-olds.
Many Americans are taking student debt with them into old age too. At the end of September, 1.8 million borrowers age 62 and older owed $62.5 billion in federal student loan debt and those in the 50-61 age group owe $213.6 billion, according to data from the Department of Education. In just one year, the aggregate amount owned by borrowers over the age of 50 increased by $28.8 billion or 11.6 percent.
TL;DR: Lots of people owe lots of student debt