Business Ethics

I do not understand why there are so many people that are willing to screw over so many other people for the possibility of an extra buck. I actually overheard a conversation the other day in which I heard a man say that it was 'bad business ethics' as a computer technician to tell your client how to use antivirus programs. He actually used the term 'bad business ethics'. I am still struggling to comprehend the selfishness or the stupidity of this man. He obviously does not realize that every time he screws someone over he is ultimately reducing his own potential business. I wonder what his opinion would be if the salesman selling him his next car used 'good business ethics'..