Paul and Ian each buy a $500,000 house with the same $400,000, 30-year mortgage at 7%. Each puts $3,661.21 per month toward the mortgage and investments.

Paul sends an extra $1,000 to principal. He pays off the loan in 14 years and 7 months, then invests about $3,661 a month. Ian invests $1,000 from month one.

Assuming steady 10% annual stock returns, Ian finishes 30 years with $2.063 million invested versus Paul's $1.546 million. That's a gap of about $516,000, even though Paul contributes nearly twice as much to investments. Ian's fourteen-year head start does the heavy lifting.

The result changes with the return. The break-even is about 7.23% annually before taxes and fees. Below that, early payoff wins this comparison. Above it, investing wins.

Liquidity matters too. Ten years in, Ian has about $200,000 invested while Paul has more home equity. A decline can cut Ian's balance sharply, but he can sell investments to cover payments or other expenses. Paul needs separate assets, new income, or financing to reach his equity.

Paying off the mortgage lowers your future bills. Keeping affordable debt can leave more capital invested and accessible. A sound FIRE decision compares both consequences.

https://www.firebtc.io/p/i-will-never-pay-off-my-mortgage