Let's say your mental landscape is similar to that of Colby Sue Weathers back in 2012: suicidal, homicidal, paranoid, schizophrenic. Oh, and with a drug and alcohol problem. You are too disabled by mental illness -- schizophrenia was diagnosed in 2011 -- and recurring hospitalizations to work. You are not great about maintaining your psychotropic drug regimen, which you administer inconsistently and sometimes to woozy excess. And you have an occasional hankering, occasionally satisfied, to consume a fifth of liquor. In other words, your life is utterly out of control.
One trouble you probably don't have -- provided you live in the U.S. -- is gaining access to a lethal firearm. Thanks in part to the advocacy of the National Rifle Association and other gun-rights groups, and in part to the commitment of elected representatives in Congress and statehouses, you can buy a gun and kill someone, yourself included, almost entirely free of obstacles. In many cases, you can do so completely legally. Because in practice, the U.S. gun market generally does not discriminate against a wide array of pre-existing conditions, including madness.