The author is doing a lot of work to explain that the statistical average takes a long time to converge to the expected return because the distribution is volat

The author is doing a lot of work to explain that the statistical average takes a long time to converge to the expected return because the distribution is volatile (high stdv, skewness, kurtosis, etc). Do note however that his analysis only concerns itself with the US. Including other countries would show that US is one of the few countries where stock markets were never interupted for a long period of time because of its political stability. If you dont beliveve it will keep going this way in the future, invest in other countries.