It turns out the better you are with numbers, the better you are at spinning those numbers to conform to and support your beliefs. - Annie Duke

when we quit things, we usually follow the idiom out of sight, out of mind. We don't naturally track things that we're no longer in. This is likely what is causing the problem with the portfolio managers. When they enter into a position, they're tracking that every day, because it's part of the portfolio. But once they exit, they're not tracking it in the same way, because the position is now off their books. It's no longer part of their P&L statement, not as far as they can see in any obvious way.

The decisions we make in our lives — in business, saving and spending, health and lifestyle choices, raising our children, and relationships — easily fit von Neumann's definition of "real games." They involve uncertainty, risk, and occasional deception, prominent elements in poker. Trouble follows when we treat life decisions as if they were chess decisions.

If you put individuals together in the right way, such that some individuals can use their reasoning powers to disconfirm the claims of others, and all individuals feel some common bond or shared fate that allows them to interact civilly, you can create a group that ends up producing good reasoning as an emergent property of the social system. This is why it's so important to have intellectual and ideological diversity within any group or institution whose goal is to find truth.