Walmart is constantly evolving to avoid dying off, as plenty of other retailers have, according to the company's chief executive officer. "Walmart is not arrogant," CEO Doug McMillon said at CNBC's Evolve Summit in Los Angeles on Tuesday morning. "We could go away at any minute. I think most of us act that way every day. If you're not willing to fail — and we are failing at some things — you're going to go away."