To expand, seriously, pretend that you are buying an annuity providing a guaranteed, life-long annual payout equivalent to a teacher's salary in your town. It's

To expand, seriously, pretend that you are buying an annuity providing a guaranteed, life-long annual payout equivalent to a teacher's salary in your town. It's a slug of cash that will make you blush. For example, https://www.bankrate.com/calculators/investing/annuity-calculator.aspx https://www.bankrate.com/calculators/investing/annuity-calcu... tells me that a $30K/year annuity good for 30 years will require more than $500K of principal at a 4% growth rate. This is a coarse approximation.