I’ve never heard 10% it’s close to 5% if you account for inflation

From what I see, I'd bet the author is not taking into account dividends and other things. What you should look at is the "Total Return" c.f. https://tradethatswing.com/average-historical-stock-market-r...

Dimson, Marsh and Staunton have been compiling the most comprehensive analysis of historical returns across all major asset classes for many years.

https://www.ubs.com/global/en/investment-bank/insights-and-d...

From the summary:

US real returns (1900-2024):

Stocks: 6.6%/yr annualized, Bonds: 1.6%/yr, Bills: 0.5%/yr

But it is noted:

> The 21st century is now 25 years old. Measured since the start of 2000, stock returns have been lower than over the 20th century, though global equity investors still enjoyed an annualized real return of 3.5% and an equity risk premium relative to bills of 4.3%

Isn’t this just the stock price going up by 10%? There’s no deeper meaning beyond that.