For the small percentage of people who are self-important pricks, the first shift of a retail job is enough to make them go "I am too good for this shit." And usually you will never see them again. Here's the thing though: everyone is too good for this shit. The first thing you leave at the door when you clock into a retail job is your dignity. You are initially saying "yes, please hire me to provide a service to other people." You think it's bad having one boss? Imagine having hundreds. That's what customer service is like. And for most of us, it's a humbling experience that teaches us that a little kindness and patience goes a long way... because chances are someone who was totally nice to you made your job a little easier.
4. A little humility never hurt anyone