> always win

That's not true. It's only been true on American stock markets, and we only have ~100 years of data.

Many other major stock markets in the world have had ~20 year periods where you would have been better off with your money in bonds than in stocks.

I think the average world stock market is a much better predictor of American stock markets over the next 100 years than past performance of American stock markets. The last 100 years have been exceptional for America vs the world -- it seems very likely that the next 100 years won't be.

The most extreme example is Germany 1914. If you would have invested in the German stock market in 1914 it would have taken you 100 years to break even. I'm not saying that American stock markets will be that bad, but it's an example that disproves the thesis that long term stock markets always win.