The worst 20-year investor experiences across major countries all share a common trigger: political/military catastrophe → financial system destruction. The -100% outcomes (Russia, China, Germany) involved the complete elimination of existing financial markets and property rights, not merely price declines. For a quant: this is the left tail that standard risk models exclude — permanent loss of investable market through political discontinuity. Geographic diversification and holding assets in multiple legal systems is the primary hedge. No country was immune: even France and Italy (WWII allies) experienced -75% to -93% returns during 1930–1950.