About the same as needing my CCW to defend myself at the shopping mall. Yet most of us still carry a concealed handgun, do we not? Thanks for confirming my point about statistics and playing the odds. Like I said, it's real easy to say it'll never happen, until it does. This logic can be applied to anything. You can be real glib about carrying a flashlight until you need one. A reload, until you need one. A backup gun, until you need one. We all have to make our own decisions about chances and risks we are and aren't willing to take. Those who have had optics fail are less likely to take chances regarding them. To me, this issue in particular, is one of the easiest no-brainers imaginable. For it is NO trouble whatsoever to equip your AR with back-up sights. Besides, is it really as unlikely as you think? Do all the high end optics manufacturers not have repair departments? By your logic, the odds of one failing are so statistically insignificant, companies like Leupold, Burris, Nikon, Aimpoint, etc., should hardly ever have to fix one.