New figures show the U.S. government is reaping a huge windfall off of the interest on student loans. The Congressional Budget Office is forecasting a profit of $50.6 billion from the interest it charges students paying back their college debt. The figure is 43 percent higher than an initial estimate of $35.5 billion. The news comes days after Democratic Sen. Elizabeth Warren introduced a measure that would lower student loan interest rates to 0.75 percent — the same rate given to big banks. Rates for government-subsidized Stafford student loans are set to double in July to 6.8 percent.