Crazy people (no I won't be politically correct) are highly motivated people.
Highly motivated people are tough to beat. They don't have an "off" switch and will push through when others would quit.
Laws, restrictions and "rule making" by government officials will never beat a determined, highly motivated individual.
That's why gun control will never work....
Sidenote: Read about Charles Whitman here. Its really fascinating. He had a brain tumor. Drugs, damaged brains...its obvious that something biological or chemical or both is pushing people over the edge. You can regulate the drug part but you won't be able to stop it as long as people want it. Mass murderers will always exist as long as mankind exists.