it doesn't take a placard, just a smidgen of empathy and the kind of theory of mind one is supposed to develop around age 12. with the exceptions of targeted attacks like those that cops and gangs do, people are not breaking into homes to do violent crimes, they're doing it out of desperation for property and capital. the vanishingly few people who are seeking out victims to rape and murder do so in isolated, publicly accessible areas, not in their homes.
maybe my original point should have been clearer: my belief that human life is more valuable than property, even somebody i don't know (or somebody you might dehumanize by calling a "criminal") against my own property, is not simply one that applies to my refusal to own a gun, but one that i believe should inform gun policy in this country.