Then, when the unthinkable happens - the way it did this week, when Miriam Carey tried to drive onto the lawn of the White House and was later shot dead by Washington, D.C., police officers - we say, "How could no one have seen this coming?"
It appears that many people did see this coming - not the violence of Carey's death, perhaps, but her unraveling.
Carey's mother told ABC News that her daughter was suffering from postpartum depression. The father of Carey's child says he called police in a panic last winter, worried Carey would hurt their infant. And Carey, a dental hygienist, was fired from her former workplace for combative behavior (though "nothing in her behavior would have led us to think this would have happened," her former boss told NBC Connecticut).
By the time Carey led police on a high-speed chase through the capital, she was said to be so delusional, she believed that President Obama was communicating with her.
The awful run-up to the young mother's death is wearily familiar to psychiatrist Lloyd Sederer, author of The Family Guide to Mental Health Care.
"I'm not at all surprised that this final, tragic event was heralded by months or longer of growing problems that were apparent to people close to her," says Sederer, who is also medical director of the New York State Office of Mental Health. He dubbed family members as "first responders" in an article he wrote for The Atlantic last year about the need for better early-warning systems in treating the mentally ill.
"When you unpack these episodes, what you see is that this is an often mounting course of illness that, for whatever reasons, goes unresponded to - even when family can see their loved one getting worse," Sederer says. "So the question is, how do we mobilize the right people to get someone into care and keep them in care? And how do we find the resources to enable them to stay in care?"
Only 20 percent of those with a serious mental disorder get properly diagnosed and effectively treated, says Sederer. Think about that: An unacceptable 80 percent never receive treatment or services at all.
Those miserable odds would improve if the stigma of needing help were reduced in the first place, says Joe Pyle, president of Philly's own Thomas Scattergood Behavioral Health Foundation.
So Pyle is particularly disturbed by how the media - in the wake of recent high-profile violent acts by mentally ill perpetrators - now "contextualizes" these sort of tragic events to show that mental illness and violence are always linked.
But the truth is, not every mentally ill person is violent, and not every violent person is mentally ill.
In Carey's case, he says, "We have a woman who was distraught, who had no gun and who may been suffering from postpartum depression - a very treatable illness - and yet her condition yielded a violent response from the police."
While Pyle isn't necessarily second-guessing the police response (once you attempt to breech White House security, perhaps all bets are off), he's nonetheless worried that this event is yet another case where mental illness was intertwined with a presumption of violence. And he fears we will become more comfortable reacting with violence to the mentally ill - not because we're actually threatened, but because we fear we will be.
"How much differently would this woman's life have been if she had accessed good mental-health care - instead of the White House lawn?" asks Pyle.
And if the true first responders in her life - her family, friends and co-workers, and not the Washington, D.C., police - had known how to help her?
On Twitter: @RonniePhilly