Myself, I think it is a very common human condition to be fickle. It is enhanced when you are personally comfortable and unthreatened, as most Americans are. Many people are completely self-absorbed and simply are not interested in anything outside their immediate sphere - unless whatever is happening is happening to them. After all, the Twin Towers didn't happen to them, so they will quickly forget it!
Gritty, I think you hit the nail on the head. I am having less to do with some of the people I used to call "friend" because they are so stuck in the "social issues" part of these campaigns that they can't see the bigger picture. (If we suffer a more serious attack, as many say we will, the rest won't matter.) They are not only willing, but they are eager to vote on the basis of social security or other benefits. That usually translates to voting for a 'rat, selling out their country for empty promises.