Unfortunately, I think the kids' lifestyle has contributed to any poor behavior they are exhibiting. They go on fancy trips, they have "staff" that follow them around. People literally jump through hoops to keep the kids happy so they can get the shot they want for the show. They get interviewed about every aspect of their lives.
I can see how some of the kids, through no fault of their own, could have developed an "I'm better than you, I'm special and you're not, I'm entitled to everything and you're not, I'm on TV and you're not, my clothes are better than yours, my house is bigger than yours" attitude. I can also see how this attitude can carry over into bullying if they verbalize it to other kids. It's sad. I think it's time for them to kill the show and focus on being a "normal" family. It's got to be hard enough to help the kids adjust to the divorce without inviting cameras to follow them around.