Personally I've always had the impression for the yanks I've met and talked to, that they have a complex compaired to you're average European. While it would be unfair to say the majority of americans are abnormal, I would certainly say that compaired to the average European they are 'insecure'. Perhaps this comes from being a young 'mongrel' nation, but their need to walk about making huge displays smacks of insecurity.
PS, Sorry if this post dont make much sense, but I'm having problems translating thoughts into coherent sentences today.