And unfortunately, some people refuse to believe the reason we're fighting even if reminded. It's sad how many people believe in the silly conspiracy theories. Some people are just so anti-American or hate President Bush so much that they'll believe anything that makes him or the country look bad.
Some people are also not very bright. I say this in all seriousness. The average IQ is about 90-100. On a bell curve, a sizeable number of people would fall both below and above that point. It helps sometimes to realize that a sizeable portion of the population has a below 90 IQ.