[ChuckMcM]

It sounds like you missed the key point "some of that money is going to principal".

Let's say you bought a house for $100K and for this argument it can always sell for $100K. And you have a 30 year fixed mortgage on it (debt for 30 years). After paying on that debt for 10 years, the principal remaining on the loan is down by about 20%. Now if you sell the house for $100K, you get back in cash $20K.

See how that works? You "saved" $20K over 10 years by making mortgage payments.

It is a little trickier with student loans because really what it means as you pay down your student loans is that you "owe less". Conceptually, if you decided to zero out your accounts, pay all your debts, sell all your assets. Then the amount of money left over would be "more" if you had spent 10 years paying down your student debt than if you had not. That difference is calculable and adds to your "net worth" (your cash value after zeroing everything out).