I figure if people (primarily adults) have no respect for their own lives then who am I to upset the balance of nature. I look at it as Darwinism - "Natural Selection" if you will. If my life or the lives of those close to me are endangered then I have no problem using deadly force. I would likely intervene if the intended victims were children but adults who know better who refuse to defend themselves only reinforce my view of the laws of nature where it's "survival of the fittest" and the weak are removed from the gene pool therefore improving the species.
When you're born you get a ticket to the freak show. When you're born in America , you get a front row seat. - George Carlin