1. this is obviously not going to stop the actual issue; calling people delusional over a strawman is pretty disingenuous.
2. Clearly there's mental illness and lack of gun control at play. There are candidates who try to address this in their platform. There are media outlets mentioning/discussing this. People want free healthcare, i.e. free access to mental health resources.
3. Talking to these people over the course of hundreds of years hasn't helped, but you're welcome to stop by *chan and have a logical debate with them. These are people who think their race is being targeted and that their race & culture is being destroyed, so I'm excited to hear the results of your well-reasoned and perfectly-logical debates.
While you're having your debates, I'm sure people will be happy to have these extremists congregate on an easily-available website like 8chan (not applicable at the moment, obviously) and also hope they don't have to dodge bullets while they're celebrating garlic, trying to get groceries at walmart, or wherever the next shooter is gonna bring his toys next.