I've actually thought that through, with other things I EDC as well, such as flashlights. The way I see it, the things you EDC become second nature, for instance a knife clipped to your pocket or a flashlight on your belt. If you're in a situation where you need your PSK, something drastic has happened. During that period, you may not have noticed losing something that's "always there". The PSK, while often "always there" might be slightly larger and more noticeable than individual items. Just my take.