Dow Jones Return Since 1930

In the near term, it's clear how buying at a market high or low can affect returns.  If you had bought the S&P 500 in October of 2007 you'd be down 10%, but if you bought in March of 2009 you'd be up over 100%.  People tend to think that over long periods of time the difference will even out.  Below is a chart of the Dow going back 100 years showing the difference between buying at the peak in 1929 and the trough in 1932.  Over the course of 80 years the difference is about 300bps annualized.  This is the difference of multiplying your money 33x and 321x.