I do not think you can segment Engineers different from the society & Humans in General ... There are Arrogant people everywhere, those who think they are in some way better than others. Not just that, they think everyone else is stupid :)
Tbh I would expect higher intelligence among engineers vs the general public if only due to selection effects. Smart kids tend to be more pushed towards professions under that label and are better able to meet the challenges associated with getting a job there such as earning a degree or learning enough to be useful.