George Carlin: Everyone who drives slower than you is an idiot, and everyone who drives faster than you is an asshole.

It's a good joke, but isn't that accurate? If I'm driving at the proper speed, anyone driving faster or slower is wrong.

What's the proper speed? If the majority of traffic is going 70 in a 65, and you consider the speed limit the proper speed, to the majority trying to squeeze around you: you're the idiot.

If you consider "the going rate of traffic" the proper speed, then everyone going the speed limit will look at you as the speeding idiot.

What absurd statement. Speed limit isn't "proper speed." It's even called a limit. You go rate of traffic, faster or slower as they adapt. Yes that means going over or under the limit.

Sometimes people facemashing into the keyboard also reveals idiocy.

First you have to define proper speed. At least in the US, it's not the posted speed limit. It's condition-dependent (rain, fog, etc)