So because of what was probably one employee with a bad day you're no longer getting pizza from what I can assume was one of your favorite pizza places (since you're such a repeat customer)? I agree that the employee's behavior was despicable, and he deserves to be fired if he talks like that to every customer, but even if every single customer of that place just up and stopped going to it the place would never know why. Like another poster said (don't remember who, and didn't see the post on a quick re-read), they can't tell whether people hate their service or their special sauce or the color of their logo unless somebody tells them.
Boycotting some random place (especially when you're probably the only one doing it) hurts no one but you. Boycotts only work if they are organized and the company knows why they are being boycotted.
Sure, you can vote with your wallet, but they will not "get the message" if you don't somehow tell them why you're walking away.