The basic basis for why Stu switched from gin to poker was that he was a bit too good at it. So skilled in fact, that no player was able equal him. Even the so-called professionals who were supposed to be the greatest at gin were beat when they faced Stu. One of these gin masters was Harry Stein, called, "Yonkie". Harry suffered such a humiliating blow at the hands of stu that he evidently quit participating in it as a pro and never showed up at a gin rummy tournament.
Accordingly, with a reputation like that it wasn’t very long before players became afraid of betting against stu. He couldn’t find any games and in his agony he began doing something no one had performed prior. He presented starting handicaps to likely adversaries in the wish that they might compete with him if they believed they had an advantage. He at will played from a disadvantageous arrangement and one story has it that he even played with a consistent cheater. During the game, he received a few words of wisdom that the cheater was at it once more but stu assured that he deduced of the dishonestly and he would still come away with a win, which of course, he did.
The same trend followed Stu Ungar into sin city. He won so much that the casinos began asking him not to bet on their casinos anymore. The reason for it was that other poker room players refused to be seated at the poker table if he were seated.
Stu Ungar is remembered more for his abilities in texas holdem poker but he always maintained that he was considerably more accomplished at gin rummy.
He beat Doyle Brunson in the WSOP in 1980 to become the youngest world champion. Due to his looks that made him seem far younger than he was, he was nicknamed, "The Kid".