You conveniently ignored half the problem by buying in 1929 and holding for 88 years, which is reasonable if you are currently about 140 years old.

If not, look at http://www.macrotrends.net/1319/dow-jones-100-year-historica...

Let's buy in August 1929 at 5338.69, and sell 20 years later, in August 1949, at 1822.87 (inflation-adjusted). Congratulations, you lost two thirds of your money.

Sell 30 years later instead? August 1959, at 5525.23. Wow, after 30 years you're up almost 3.5%!