The following paragraphs:
>" Johnston provides a realistic insight into the working of Jess�s mind as Jess combines his mathematical prowess with his (self-taught) psychiatric skill to harpoon the Whale.
In view of these extensive previous accounts of this episode, I am only going to summarize briefly Jess�s part in it. He described the whole thing rather succinctly to me. He said that in winning the first $6 million, the Whale had simply not played enough hands (700) to have a high probability of losing. Therefore, Jess advised the Trump people to just �let him play�. Although they were very nervous about following this advice, they did and ultimately the Whale lost $9.4 million.
I learned from the written accounts cited above that there were two key components to Jess�s analysis of this problem. First, he calculated that if the Whale could be enticed into playing 5000 hands or so, he would have only about a 15% chance of winning. However, since the Whale made a practice of quitting suddenly if he was winning significantly, a scheme was needed to ensure that he would not quit early. Based on observing the Whale�s mannerisms at the gaming table, Jess concluded that the Whale would readily agree to a double-or-nothing rule; that is, play would end only when the gambler had either doubled his bankroll or lost it all. Jess calculated that the Whale was 5 times as likely to lose his bankroll as he was to double it."<