Correct -The math (Assumes no taxes for anything):
SMF Scenario:
Keep paying the mortgage at $1k per month for 10 years = $120k expenses
Invest $100k at 5%, reinvesting gains monthly = $164.7k future value
SMF Net gain = $44.7k
Souf Scenario:
Pay off mortgage = $100k expenses
Invest 1k per month at 5%, reinvesting gains monthly = $155.9k future value
Souf Net gain = $55.9k
Souf is right.
But wait
At a return of 7% rather than 5%:
SMF Net gain = $81k
Souf Net gain = $74.1k
SMF is right.
Souf has no taxes until the end
Smf pays taxes every month on his withdrawl of investment .
Souf also has no mortgage for a decade .
Because souf lives in the real world .