That has historically not been the case ever.

This is said by people in a self congratulatory way, who parrot bad advice as some deep truth, but even the most cursory glance at any long term market data shows with zero doubt that you are dead wrong, not only regarding many markets around the world, but also American markets

Here's the 100 year dow chart: https://tradingeconomics.com/united-states/stock-market

In July 1929 it peaked around 380. That level would not be reached again in nominal terms until the mid 50s. But there was also a lot of inflation in the 40's, so not only were you losing money, that money was losing value. So you lost in nominal terms and got devastated in real terms over 25 years.

Now let's look at Sep of 65. The dow is at 980. It won't recover that level until 83. Again including the inflation of the 70's. Stocks got destroyed in real terms over that 18 year period.

And many many stock markets around the world have uglier periods than that. Also many forecasters expect the 2020's to have some of the worst equity returns in modern history.

So as I said, unequivocally this is a false idea.

You’re not factoring in dividends. Dividends are a crucial component of returns of indices.

Someone who bought the market at its peak in March 2000 has earned a 6% compounded return since then.