violent video games are certainly not the reason people go on shooting sprees. There obviously mental health issues as well as possible personal trauma that are the main reasons.
That being said, it isn’t like there isn’t a correlation. Most of these shooters are drawn to violent video games and they can help dehumanize and desensitize the idea of a real life massacre. However, these people have to already be ill or unhinged.
Honestly, if congress really wants to curb these mass shootings, the most effective thing they could probably do is outlaw news coverage of them. That would be far more effective than getting rid of violent media. If a shooter knew they wouldn’t get their 10 seconds of fame, these events would be much more rare.