I believe it is the product of what happens when you mix people of different classes and group them all together.  

People who bully sometimes do this as a coping mechanism to mask their own insecurities. There are a lot of bullys out there unfortunately. Fortunately now that we are all adults it would seem that the insecurities the bully was successful in masking whilst he/she was younger now would come to light.

In most instances you will most likely find that a person who bullies lack bravery themselves. In an open forum such as this a lot of times you will find people putting themselves out there. Basically, putting their thoughts and feelings for public display with the intention of learning how his/her piers would relate. Put simply bully cannot do this. Instead the bully will criticize,  become defensive, and if challenged become aggressive. He or she lack the social skills necessary to disagree while still being subjective and respective of another person's point of view when it differs from their own.

This is not just my 2 cents.