Law 1: Always and inevitably everyone underestimates the number of stupid individuals in circulation.
Carlo Cipolla, The Basic Laws of Human Stupidity
This may seem like an uncharitable exaggeration, but one is repeatedly surprised by how individuals that you once considered intelligent turn out to be unashamedly stupid. And one is also surprised to see that, in a vast number of situations, you find the existence of stupid people in uncommon and surprising situations.