Yes. Killing will make them feel like God, and this has been te same with most school shooters. After the shooting, most of them say that they actually felt good. So I think if there is no bullying school shootings can totally be prevented. Rejection from family is one factor too. Most school shooters come from families divorced and such.
There are many people in this world who struggle with different aspects of their lives. It can take something very small to finally make them snap. Bullying has contributed to many shooters doing what they have done. When someone is broken down by others day in and day out they become a different person who is not rational or normal.
I think that when someone is bullied and rejected by their peers, it causes them to feel so cast out and angry. That is why most people would turn to that option. Just look at the Columbine kids, that was absolutely a reason for them to become serial killers in that awful shooting.
Bullying and rejection often lead to feelings of powerlessness in their victims. If a person doesn't feel as if they have any outlet to express those emotions in a healthy way they may begin to fantasize of violence as a payback. It's important to encourage young people to accept themselves and others in order to avoid these kinds of tragedies.
If we are talking about mass shooters only I would say that they have a deeper sense of isolation or rejection from the world at large. People who are bullied or rejected in their own social realm seem more often to internalize the feelings and take it out on themselves via suicide, whereas a mass shooter wants to go out in style and kills at random.