<p>It depends on many factors. The mortgage interest deduction decreases as one's income increases above certain treshold levels. Any levereaged position, (20% equity), is advantageous on an appreciating asset, and theorectically, if one can invest at a better rate of interest than one pays, it is better to borrow to invest. Bottom line, one is borrowing on the equity in one's home to invest at a better rate of return than the interest rate one has to borrow at; kind of what banks do, eh?</p>
<p>I say theorectically, because the scenario as you and I are portraying disregards human emotions and unforseen financial events. In my experience, 70% of the success of investing is due to controlling one's emotions and only 30% is due to the actual investment and the circumstances surounding that investment. And in my estimation, the best way to remove emotion from financial decisions is to remove leverage and debt.</p>
<p>Example : Let's say I own a home with a market value of $1 mil with no mortgage and I also have $100,000 to invest. I can invest the $100k with no pressure due to the thought that if I don't have a particular ROI, I will have to move or borrow more or ...</p>
<p>Let's say I own the same $1 mil home and I borrow $800,000 on it to add to my $100,000 for a total of $900,000 to invest. I posit the decisions I now make regarding the investment of those funds will now be clouded by the pressure of the threat to my living situation. I now am pressured to stay employed, not fall seriously ill, make an ROI greater than my mortgage interest, etc.</p>
<p>If you know anybody who is wealthy, ask them if they think you should pay off your home or invest in other asset classes, and ask why. People borrow because they have to, not because they want to, imo.</p>