Denigrating your customer's repeated complaints the way you do is what the problem is. You just don't seem to get it, or if you do, you don't care. Your buddies can pat you on the back and tell you that all these people are whiners, but it doesn't change the fact that your actions and postings are not professional - and a lot of people choose not to do business with you as a result. You can't change what others do, but you're in complete control of your own actions, and those actions are amateur and unprofessional.
Like I said, don't let the door hit you on the way out.