Rotating out of WMT/TGT, doubling down into AMZN/COST/HD: Is the "Big Box" model breaking?

Recently closed my Walmart and Target positions (minus 401k/etf) to double down into Amazon, Costco, and Home Depot. The primary thought is that the traditional big-box footprint is a liability. Between the surge in organized retail theft aka shrink and the high cost of increased security, margins are being squeezed in a way that e-commerce (AMZN) and membership-only models (COST) simply don't have to deal with. Moving capital to companies with stronger "moats" (I learned a new word today) against these specific issues. Am I over reacting?