The famous American statesman of the 1890s, William Jennings Bryan, declared,
Destiny is no matter of chance; it is a matter of choice.
From the beginning of W. W. Jacobs story until its end, the Whites make choices that determine their fates. And, much like the Frost's famous poem, "road leads to road." Indeed, it is the initial choice of Mr. White to have invited Sergeant Major Morris to his home that sets in motion what may seem the Whites' fate. And, despite the sergeant major's warning to let the paw burn after Mr. White has tossed it into the fire, White retrieves it. Even then, Morris urges him to pitch the paw upon the fire again. Therefore, the Whites have placed themselves on the path that destroys their lives. And, it is the greedy desire for money which leads Mr. White to make his wish without enough forethought for two hundred pounds and have his one figurative "road" lead to others.
However, if the reader must interpret the story in terms of the above quotation about the power of Fate, perhaps he can take the position that Fate determines that the paw be burned, and Mr. White interferes with this dictate; in short, he "tempts fate." Thus, with Fate having been interfered with, the consequences are certainly sorrowful as the cursory wish for money leads to the tragic death of Herbert and its subsequent horror for Mr. and Mrs. White.