Wasn't expecting to see my favourite author mentioned in FT...
It's actually a character in one of his books who makes this comment, the properly nasty fecker Perez in 'All The Pretty Horses'.
I think there's a more apposite quote regarding @NotTheMarketLeader going down the 'opinionated rabbit hole' that occurs a couple of lines earlier;
He sat back easily. He tapped his temple. It is not that he is stupid. It is that his picture of the world is incomplete. In this rare way. He looks only where he wishes to see. You understand me?
I understand you.
Good, said Perez. I can normally tell how intelligent a man is by how stupid he thinks I am.