The real return for bills since 1912 (the modern fiat era) has been -0.1 percent. The real return of gold during this era has been 1.6 percent. You would only have made a positive real return holding interest-earning cash currency in about half of the countries during this era, and you would have lost meaningfully in the rest (over 2 percent a year in France, Italy, and Japan, and over 18 percent a year in Germany, due to the hyperinflation).
