Protein-maxxingProtein has become the new low-fat. Supermarkets are rapidly adding protein to everything from Pop-Tarts and Doritos to Starbucks drinks and now even beer. Demand has rarely looked stronger as GLP-1 users, longevity enthusiasts and gym-goers all chase muscle preservation. Yet while consumers are buying more protein than ever, Wall Street's pure-play protein stocks have collapsed. Here's why investors may have correctly identified the trend—but bought the wrong part of the value chain.Why is this relevant?