Why do so many Americans think they're so superior?

For example, they correct British spellings of words, which were around for a long time before Americans changed them, they correct the British way of writing the sate (day/month/year) even though it makes more sense, and I have heard many bad comments towards Catholicism also - yet another disrespect for something that came BEFORE their denominations of Christianity. Protestant and Evangelical faiths would not exist without Catholicism.