Costco currently trades at 43.3 times earnings, placing the company's valuation much higher than its industry peers. With close competitors like BJ's Wholesale Club (NYSE: BJ) and Kroger (NYSE: KR) trading at 20.1 times earnings and 32.7 times earnings, investors may be wary of Costco's high valuation. I believe, however, that Costco has earned its high-end appraisal and will continue to reward its long-term investors. Here are three reasons why.