I fell for that trap once. The statistics show people with a diagnosed mental illness are actually less likely to participate in violent crimes than the general population. Thats not to say mass murderers don’t have underlying mental illnesses but it’s easy to just assume that they do. Yet, as we already know, a person who has no mental illness is perfectly capable of violent crime.
If you try to inject this conversation into normal discourse you might be surprised how fast you discover some people’s prejudices against mental illness.