Costco (COST -0.23%) investors aren't used to being disappointed. The warehouse retailer's stock has trounced the S&P 500 over the last five years even while the company sent billions to its shareholders through special dividend payouts. Factoring in those payments places Costco's returns at over 230% -- more than double the market's 100% rally since March 2021. Those are some head-turning gains for a retailing stock that's one of the least profitable in its peer group. We're not talking about a fast-growin ...