Saying that people who enjoy sport/ gambling "don't have anything to do with people who want to cheat and steal to gain materially from it" is a false dichotomy. It's nature. Ask yourself, would you throw a game in your sport of choice in a hobby league for 100 million dollars or whatever? Why not, no one gets harmed, it is a lot of money, it's not even a proper league. This applies to all levels of real world consequences, some people have a larger apetite for risk.
In a very strict sense, you are right. But people influence other people, and people who wouldn't act this aggressively otherwise find themselves inspired to after taking a bet.
That's not my argument though. Gambling is not the equivalent of a gun in this situation. Gambling is the catalyst, sure, but the crime is making death threats. Removing all the reasons why people might make death threats in order to stop the death threats is going to be tricky.
If you want an analogy it's like the argument is 'Let's not have banks because they only encourage bank robbers!', and I'm here arguing that really we just need to make bank robbery a crime.
ATMs have long had devices that stain cash if you try to steal from them. Bank cashiers used to have "we don't have the keys to the vault" signs. Vaults that open at fixed times beyond the control of the cashiers are a thing.
Regulation and enforcement are important but removing opportunity and motive are also important.
The problem can indeed be "the asshat contingent", but at the same time, it's not blaming the victim to say that certain situations open up opportunities.
A lot of our laws are in place to prevent people from taking advantage of such opportunities. That's why some laws seem bizarrely harsh, where you can earn more jail time than physically assaulting someone, for a financial crime. Or computer hacking.
The logic is "this is an easy way to break the law", and "we'll have to make the penalty worse to compensate". That's not blaming the victim. In fact, it's an attempt to protect the victim.
This sensible approach is akin to what you'd do if you entered certain 'sketchy' sections of many cities, at 2am. You certainly wouldn't walk around carrying a big box of 100 iphones, and people would say you were nuts to go into that area at 2am and do so.
Yes, the asshats who assaulted you, beat you unconscious, and stole your $100k worth of iphones were wrong. But, you'd certainly be considered a little dim for doing so I'd think. Why?
Because you're ignoring reality for a catch phrase.
Reality is just that.
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.