The most dangerous thing in money is not being wrong.

On Friday I told you about my own certainty, and where it got me, and I left you with a hard question. If being sure and being right feel exactly the same from the inside, how do you ever know which of your decisions you can actually trust.

So I went and looked at how the best who have ever done this handle it. People who have made and lost more than most of us will ever touch. What I found was a strange kind of comfort. Every one of them has been completely certain and completely wrong, in public, with everything on the line.

Ray Dalio was so sure the economy was heading into a depression in the early eighties that he said it on television and in front of Congress, and he bet his firm on it. He was dead wrong. The market took off in the other direction, and he lost so much that he had to let his entire team go and borrow money from his own father just to cover his family’s bills.

Bill Ackman put roughly a quarter of his fund into one company he was convinced would win, held on as it fell, even added to it, and finally sold years later for a loss of around four billion dollars. His own word for it was a huge mistake.

George Soros built one of the great fortunes in history on a single idea, that he is probably wrong. He has said the only reason he ever got rich is that he knows when he is wrong, and gets out fast.

Sit with that for a second. The most dangerous thing in money was never being wrong. It is being certain. The sharpest minds alive have been nearly destroyed by their own conviction, and the ones who climbed back did it with the exact opposite of certainty. They feared they were wrong. They went hunting for the argument against themselves. And not one of them did it alone.

So here is the answer to what I left you holding. The decisions you can actually trust are not the ones you feel most sure about. That feeling tells you almost nothing, because being wrong feels identical to being right. The ones you can trust are the ones that have already survived the smartest people you could find doing their level best to tear them apart. Real confidence is not where you begin. It is what is still standing at the end of that, and even then you hold it loosely, because the day the facts change, the most expensive thing you can do is stay sure.

This lands hardest at the exact moment it is least welcome. Right after a win, when the equity finally clears and the number on the statement is suddenly real. That is when your confidence runs highest and your blind spots run widest, and it is precisely when people quietly lose what took them a lifetime to build, making emotional calls, or no call at all, certain they have it handled.

You cannot outthink your own certainty by yourself. Nobody can, not even the people at the very top. That is the entire reason for the right people in the room. They can see the one thing you are far too sure to notice.

Talk Friday.

— Mateo