Empty vessels make much noise

Certain selection bias there - we only hear from the dumb people who are dumb enough to demonstrate their stupidity loudly. Though perhaps the sense to shut the fuck up is itself a sign of a certain level of intelligence that's missing from the even dumber ones.

The best lack all conviction, while the worst Are full of passionate intensity.

A good argument only needs to be said once.

A stupid one needs to be repeated over and over until it hits an ear stupid enough to believe it.

The drunken driver has right of way...

That's why I spend my free time screaming. Gotta let people know

or just the ones with the most time on their hands.

That's because smart people tend to think before they talk