The Basic Laws of Human Stupidity

  1. Always and inevitably everyone underestimates the number of stupid individuals in circulation
  2. The probability that a certain person is stupid is independent of any other characteristic of that person
  3. A stupid person is one who causes losses to another person or a group of people while they gain nothing or may even suffer losses
  4. Non-stupid people always underestimate the damaging power of stupid individuals. In particular, non-stupid people constantly forget that in any time and place and circumstance dealing and/or hanging out with stupid people always turns out to be a costly mistake
  5. Stupid people are the most dangerous type of people

Source: Carlo Cipolla