Costco's customer-first focus has proven a winning model for shareholders. Few large companies have embodied the resilience of brick-and-mortar retail amid the transition to the digital age quite like Costco Wholesale (COST 1.18%), which hit an all-time high on May 10. The stock is up a mind-numbing 576% over the last decade. It is now the third-most-valuable U.S. consumer staples company behind Walmart (WMT -0.05%) and Procter & Gamble, and ahead of giants like Coca-Cola and PepsiCo. Costco has done an exc ...