A quote from Oaktree Capital (via Will Maier)

"In deciding which future to prepare for, you need two things: (a) an opinion about what's likely to happen and (b) a view on the probability that your opinion is right. Everyone knows about the former, but I think relatively few think about the latter. In short, most people believe in their opinions. "Of course they do," you might say. "If they didn't have faith in their opinions, they wouldn't hold them." And that's the point. Everyone's entitled to his or her opinion. But one of our favorite sayings around Oaktree states that "it's one thing to have an opinion, and something very different to act as if it's right."

A tighter distillation in a recent podcast: "it's ok to have an opinion, but it's not ok to act as if it's correct"