Based on its track record of compounding shareholder capital, investors have reasons to remain optimistic.Over more than five decades Starbucks (SBUX 0.47%) has become a ubiquitous coffeehouse chain with one of the world's most recognizable consumer brands. And shareholders who've held on along the way have also been rewarded thanks to a steadily rising stock price.As of this writing, this top restaurant enterprise carries a market cap of $100 billion. That's after shares have fallen 30% from their peak pri ...