The third law: "A stupid person is a person who causes losses to another person or to a group of persons while himself deriving no gain and even possibly incurring losses."
Are you a stupid person if you do this once? Twice? Frequently? (Does anyone do it frequently?) Are any of us not stupid? And what does this have to do with the normal meaning of "stupid"?
I like this way of seeing it. All of us, at some point in our lives, have acted Helpless, Intelligent, Stupid, and as Bandits. Life and growth is learning from the past and improving where the balance of your behaviour lands in each respective quadrant.
The author has a very precise definition of stupidity. He very explicitly states that level of knowledge/education is completely orthogonal to being stupid. (As prevalent among Nobel laureates as it is among blue collar workers.) Stupidity, in his definition, appears to be an attitude more than anything else.