I have personal experience with someone who was obviously a danger to himself and those around him. He was a paranoid schizophrenic after years of drug abuse. His wife left him and took his son when he started hearing the voices in his head, but because he had not hurt anyone YET, the cops could do nothing. His mom criticized the wife for not living up to her "sickness and health" vows. So this 6'4" 300 pound man moved back in with his well to do parents. His mother kept him sheltered at home and pretended there was nothing wrong. Until the night when he cut all the power and phone lines and started shooting through their pecan orchards at the "DEA guys" who were after him. The (barely 5'10 inch) dad walked to a neighbor and called the cops. This got him a 15 day hold, but the mom refused to press charges. Back home he came. Mom had a stroke and died not long thereafter, and the other brother had his brother committed. But again, dad got him out of the hospital because the crazy guy did not like the way the meds made him feel.
So he came off his meds, got a shotgun, went into the back bedroom and listened to the voices that told him to kill himself. Fortunately his dad was not home, and they lived way out in the country, or this could have been a whole lot worse. His wife absolutely did the right thing when she left him and took their child. The mom was totally in the wrong.
In this instance, the family had all kinds of money - but they thought they could keep him at home. This VERY large man was the human equivalent of a rabid dog - unstable, prone to fits of rage, fits of depression, conversations with voices... and he refused to take his meds. Not much two elderly people could do to make him. The crazy guy belonged in a secure facility. In some instances, that's all you can do - and you owe it to society to make sure someone this damaged cannot hurt innocent people.