Americans often buy guns for self-defense, a purpose that now has Supreme Court validation. But according to advocates of gun control, those purchasers overlook the people who pose the greatest threat: themselves. Anyone who acquires a firearm, we are told, is inviting a bloody death by suicide. So says Matthew Miller, a professor at the Harvard School of Public Health. "If you bought a gun today, I could tell you the risk of suicide to you and your family members is going to be two- to tenfold higher over the next 20 years," he told The Washington Post. Since the...