What is ironic about the difference in playing of the father and son?

Mr. White is competitive and reckless..... he also cheats. His son, however, is merely having a good time.

Father and son were at chess, the former, who possessed ideas about the game involving radical changes, putting his king into such sharp and unnecessary perils that it even provoked comment from the white-haired old lady knitting placidly by the fire.

"Hark at the wind," said Mr. White, who, having seen a fatal mistake after it was too late, was amiably desirous of preventing his son from seeing it.