“Truly wealthy families do not borrow for college at all and do not hold student loans,” Kat Welbeck, director of advocacy and civil rights counsel at the Student Borrower Protection Center, told Fortune. “And when they do, they pay off debt much more quickly. The way we measure ‘progressivity’ with nearly every other social program is how benefits compare to a share of income. Student debt-to-income ratios are much higher for the poorest households, and therefore the…