Why does everybody think pitbulls are bad?

Seriously why does everyone keep saying that the pittbull breed is so bad I mean seriously I have a full breed blue nose pit and he has never bitten or attacked another human being or animal ... and now im having a whole bunch of people telling me not to walk my dog in the neighborhood because of the breed I mean seriously most people assume that just because my dog is a pit that he will attack them unlike other irresponsible owners I educate my dogs myself