I paid off my mortgage 9 years early and I'm not sure I'd do it again. Here's the honest analysis.

At a 3.25% fixed rate, paying off the mortgage early provided a guaranteed 3.25% return on that money. Over the same period, my investment account earned approximately 9.4% annually.

The math clearly says I should have invested the extra principal payments rather than paying off the mortgage. The interest savings were real but the opportunity cost was larger.

What I underestimated in my original decision: the psychological benefit of no mortgage payment was real and significant. It changed how I thought about career risks and spending decisions. Whether that psychological dividend was worth the $80,000 in estimated foregone investment returns is genuinely hard to quantify.

My conclusion: the mathematically correct answer is to invest rather than pay down a sub-4% mortgage. The psychologically correct answer varies by person. Be honest about which calculation you're actually making.