The basic basis for why Stu changed from gin rummy to poker was that he was a bit too skilled at it. So skilled in fact, that no player was able stand up to him. Even the apparently experts who were supposed to be the greatest at gin rummy were demolished when they faced Stu Ungar. One of these gin professionals was Harry Stein, nicknamed, "Yonkie". Harry Stein suffered such a debilitating defeat at the hands of mr. ungar that he evidently stopped playing it professionally and never showed up at a gin rummy tournament.
Certainly, with a notoriety like that it wasn’t very long before gamblers became afraid of competing against Stu Ungar. He could not find any matches and in his agony he started doing something no one had done before. Stu issued beginning handicaps to likely competitors in the hope that they might play against him if they thought they had an edge. He at will began from a negative arrangement and one tale has it that stu even played with a constant cheater. During the match, he get a few words of wisdom that the absconder was at it again but Stu Ungar guaranteed that he knew of the cheating and he would still come away with a win, which he did, of course.
The same problem followed Stu Ungar into vegas. He won so frequently that the poker rooms started requesting that he not to wager on their poker rooms anymore. The basis for it was that other poker room visitors refused to sit at the poker table if he were seated.
Stu Ungar is recollected better for his achievements in holdem poker but he always maintained that he was far more skilled at gin rummy.
He defeated Doyle Brunson in the WSOP in 1980 to become the youngest world camp. Because of his looks that made him seem far younger than he was, he got the nickname, "The Kid".