Right, but the mantra in the personal finance circles is "Mortgage Your Retirement" because you are borrowing all the money you will need to retire -- say $2m,

Right, but the mantra in the personal finance circles is "Mortgage Your Retirement" because you are borrowing all the money you will need to retire -- say $2m, investing it in the S&P 500 and paying that off over time. If the market goes up than you're that much closer to paying it off and retiring. The authors recommend only 2:1 leverage so only a 50% decline would wipe you out. The problem I personally have with this is the declining marginal utility of money. Losing everything (or a large portion) to squeak out better returns isn't worth it. There was someone on Bogleheads who posted about trying this, exhausting their student loans and credit cards, but unfortunately when they started it was Fall of 2007. The guy had pretty bad luck, but I'm sure it's worked for other people especially those who don't know it (e.g. "I bought options on Google in 2006!") https://www.bogleheads.org/forum/viewtopic.php?t=5934 https://www.bogleheads.org/forum/viewtopic.php?t=5934