I see, so every time you pay the interest, you're losing x% of the loan in current dollars, but the loan is getting cheaper in real value by y%, where x is the interest rate and y is inflation. So despite paying more dollars overall by the end, you're paying less real value overall. I guess the risk is that y falls below x later, at a time where you would have paid it off if you had been doing extra payment, so you increase your payments, but maybe the change could be dramatic enough to undo the benefit?