1. 'Cuz we talk funny.
2. 'Cuz lots of us were poor-boys for a mighty long time. (and po' boy automatically = stooopid in many people's ideas of how the world works.)
3. 'Cuz they can.
[That was said by a Suthun from a long line of Sunthuns & with her tongue firmly planted in cheek, so no raised hackles or wet hens, please. However, the writer herewith acknowledges the existence of half-joking/full-earnest comments. YMMV ]