In fairness to those that say you should pay your mortgage off first, if you could put an investment vehicle out there that guaranteed a three percent rate of return over the term of up to thirty years, you'd make millions off of it. And that's exactly the effect of paying off a mortgage early. It is a risk-free investment that will save you the interest you would have paid on the home.

Now, put that same money in an index fund, and you have no guarantee. You might gain; you might lose. Someone not anxious to ride that wave, or who just wants to be free of the specter of debt, may find that unappealing.

That said, in this era of three-percent mortgage interest (compared to historical market performance, commonly assumed to be around 7% in spite of all its ups and downs), that degree of risk aversion is so conservative that it borders on irresponsible.