I remember that when I was a child, my mother would call me some names which were quite derogatory, except that she said them so affectionately that nobody would take that as an insult and I certainly didn't.
Anyone with some understanding of our culture will know that she was doing what most older generation Chinese parents would do to their children - saying the opposite of what they wish for their children, for fear that if they extol their children's beauty or virtue, the gods will be jealous and take those qualities away. Saying that their children are "ugly" or "stupid" may, they believe, spare them of that misfortune.
He may not exactly be referring to this Chinese way of thinking, but in his book Enthusiasm Makes the Difference, Norman Vincent Peale makes the following comment about this sort of mentality:
"Here again was that curious quirk of thinking, that if one talks negatively, the opposite is more likely to occur. So in this man's mind was a strange, conflicting mixture of anxiety tinged ideas, which he feared yet didn't believe in. But he did believe in them enough to be dominated by them. The result not only caused unhappiness, but also an enormous leakage of mental energy that might have been employed for constructive purposes."
That may explain why we are in general a sad people who like to wallow in self-pity.