Ignorance is like a disease, the more it is spread around, the more people are inclined to believe such things. Plus, people are way too absorbed in the media, and don't bother looking beyond the TV for some credibility. It could be because some people are lazy, and don't want to try and look for individuality.
As for Britney, don't listen to her, she is not making all White people look bad, just herself. The White man made the gun, and a Black man made the stoplight, so I wonder where people would be without that little invention.