The speaker cited data showing the S&P 500 has been profitable approximately 81% of the time over all 3-year rolling periods since 1871. For a medium-term (3-year) goal like a down payment, mixing the S&P 500 with cash provides a high probability of positive returns while acknowledging and planning for the ~19% chance of a drawdown. WATCH the S&P 500 as a viable component for medium-term investing, but its use requires an explicit, upfront acceptance of the risk of capital loss within the timeframe. The investment horizon coinciding with one of the historical ~19% of 3-year periods that resulted in a loss.