You've probably heard the phrase 'don't put all your eggs in one basket,' and it applies directly to where you invest your money. The US market has absolutely crushed it over the past decade, delivering returns that make global competitors look sleepy by comparison. But here's the thing: past performance doesn't guarantee future results, and the earnings potential you'll actually see depends on what you're looking for. Should you stick with American companies or spread your bets across Europe, Asia, and emerging markets? That's the real question.