You're taking it much too seriously, that says something coming from me. Violence perceived is not violence received. Just because someone might play a violent or aggressive thing, which nearly every sport ever invented could be along with dozens of other things, doesn't mean it's going to warp someone into a killing machine. What actually causes shootings is a lack of awareness about Mental Health because the United State's views on it are very underdeveloped. People with impaired mental faculties are often found to be the one's that cause those issues. Some part of their brain did not develop properly, like centers that maintain empathy and foresight(the ability to think about what an action might do), oftentimes impacts those people. That's why you often hear from people related to or knowing of someone that does a shooting, that they say "He/she never seemed like someone to do that, this was so sudden." When it's not actually, people just aren't paying attention to someone's changes mentally. That's all that needs to be done, otherwise playing Dodgeball or Laser Tag will never make you want to harm someone all by itself.