Why do some police officers think they above the law and believe they have the right to talk to you like crap?

Why do they think even when they're off duty they can stop whoever they wish, talk to u like s.hit and then expect you to be polite? If you treat them like you they can click their fingers and arrest or fine you. I'm sick of them, NO i've never been in trouble with the law but today I was stopped by a man was off duty and I was only crossing a pavement to get to the road. He ordered me to apologise to him, dismount my bike and give him an explanation, he was patronising, condescending and rude. He said, "it was a pleasure meeting you," and then said, "off you go." If I dared spoke to him the way he spoke to me he would of had the power to arrest me. If police spent more time focusing on rapists, murderers, terrorists and muggers than biking on the pavement (been knocked by a car twice in last month and yes I know how to bike, both were sent to car training by police) and other petty s.hit e.g speed cameras perhaps society would be a better place! Police arent above the law! opinions?