>My experience has been that this isn't limited to engineers.

To some extent, but the most severe form does seem fairly unique to engineers, specifically programmers. That is, I've met many arrogant lawyers and doctors, but never a lawyer or doctor who assumes they could program a computer due to their legal or medical expertise. But I've seen many a programmer assume that because they are proficient in programming they can confidently and authoritatively expound on all other areas of human endeavor (those being obviously inferior and trivial in the face of their own).