The existence of something in no way encourages someone to commit a crime. That is victim blaming (if the concept of 'sport' can be a victim in this case). Sport and people who enjoy sport and people who enjoy gambling on sport don't have anything to do with people who want to cheat and steal to materially gain from it. If you banned sports those people would just move on to some other criminal enterprise to get rich with minimal effort.
In what's happening in the story the fact that people are gambling on a war is certainly quite grim, but it's not really a problem. People do distasteful things all the time. The problem is that they're issuing death threats to someone. That's not really anything to do with gambling.