The basic basis for why Stu changed from gin to poker was that he was a little too good at it. So good in fact, that no one possibly could stand up to him. Even the commonly called professionals who were supposed to be the most favorable at gin rummy were crushed when they competed with Mr. Ungar. One of these gin rummy player was Harry Stein, called, "Yonkie". Harry Stein suffered such a crushing beating at the hands of stu that he apparently stopped participating in it as a pro and never showed up at a gin rummy tournament.
Of course, with a image like that it was not very long before players became shy of playing against Stu Ungar. He could find no matches and in his bleakness he started doing something no one had performed prior. He provided starting handicaps to likely adversaries in the high hopes that they might play opposed to him if they thought they had an advantage. He at will began from a negative arrangement and one story has it that stu even played against a consistent absconder. Amid the game, he get advice that the cheater was at it once again but Stu Ungar stated that he knew of the cheating and he would still come away with a win, which of course, he did.
The same trend followed Stu Ungar into Las Vegas. He won so often that the casinos started asking him not to gamble on their respective premises anymore. The reason for it was that other poker room players would not sit at the table if Stu was seated.
Stu Ungar is remembered better for his achievements in holdem poker but he himself always said that he was considerably more accomplished at gin rummy.
He beat Doyle Brunson in the World Series of Poker in 1980 to become the youngest world champion. Because of his features that made him seem far younger than he really was, he was nicknamed, "The Kid".