Good comments. You know, I am a little bit more optimistic about society than many. I think 75% of people are decent, and I think that 75% would eliminate the 25% of slugs through good old fashion frontier justice, and Darwinism at its best. Things tend to take care of themselves in an emergency.
I wouldn't consider myself a prepper, though I do have an abundance of those "staples" you mentioned. It's just good common sense to have a stored survival supply that can last you a year. If the SHTF scenario is bad enough that it lasts past that, you got to wonder if life is worth living at that point.
Actually, the 75% would only have to eliminate about 1% of the slugs and the rest would quickly decide that at least pretending to be honest citizens is a better alternative, after all.