He's a very smart man who knows a lot about human intelligence. He's a brilliant psychologist and a Nobel-prize winning economist. Early in his career, he advised the Israeli military on how to train fighter pilots (presumably not on how to fly planes but on how to make good decisions). In 2005, he was voted the 101st-greatest Israeli of all time, in a poll by the Israeli news website Ynet. In 2011, he made the Bloomberg 50 most influential people in global finance. He has written a book titled Thinking, Fast and Slow. So you get the idea: he has studied extensively the human mind and the way we think. His name is Daniel Kahneman, and here's what he said in a Time magazine interview about the quality of our rational thinking:

We are normally blind about our own blindness. We're generally overconfident in our opinions and our impressions and judgments. We exaggerate how knowable the world is ….

What psychology and behavioral economics have shown is that people don't think very carefully. They're influenced by all sorts of superficial things in their decision-making, and they procrastinate and don't read the small print.