The Bookmaker's Favorite Customer
Sports bookmakers discovered something decades ago that made them a great deal of money: fans bet on their home team. Not because they've analyzed the matchup — because they know that team. They watch every game, know every player's name, feel the team's strength in their bones. Bookmakers quietly shade the odds against home-team bettors and collect the difference, year after year, from people who mistake familiarity for information.
Now open the average investor's portfolio — in any country on Earth. American investors hold roughly 85% of their stocks in American companies. Japanese investors overwhelmingly hold Japanese stocks. Australians hold Australian ones. Ask each of them why, and you'll hear the home fan's logic, delivered with total sincerity: I know these companies. I use their products. This is the market I understand. Every investor on the planet believes their home market is the sensible choice — which is mathematically impossible, since they can't all be overweighting the best one.
This is home-country bias, and it's the bookmaker's favorite bet wearing a retirement account. It isn't a conclusion anyone reasons their way into. It's a default — the portfolio equivalent of rooting for the local team — and like all defaults, it goes unexamined until the season it costs you. Lesson 2.3 showed you the worst case in history: Kenji's thirty-four years underwater in the world's most admired market. This lesson is about the decision itself — how much of the world to own, why your instincts will fight you, and what a century of scoreboards actually shows.