To all those players who became billionaires, and also to those financial advisors that show how anyone with modest income can become a multimillionaire in a 50-year working lifespan through the miracle of compound interest:

People have been investing in property, stocks, and in interest-earning bank accounts for centuries. Someone starting with $38,000 in 17th or 18th century would be worth trillions or quadrillions today[1], or at least their descendants would be.

So where are those trillionaires and quadrillionaires?

The problem is that over long spans of time (50+ years), there are wars, revolutions, devaluations, confiscations, hyperinflationary periods, and other economic disasters that have wiped out all savings.

There's no reason to assume that these things won't happen again when projecting over long periods.

[1] http://www.wolframalpha.com/input/?i=%2438000+at+6%25+for+40...