The main basis for why Stu Ungar switched from gin to poker was that he was a bit too good at it. So skilled in fact, that no one possibly could stand up to him. Even the so-called experts who were meant to be the best at gin were devoured when they faced Stu. One such gin player was Harry Stein, called, "Yonkie". Mr. Stein suffered such a crushing beating at the hands of stu that he apparently stopped playing it professionally and never showed up at a gin rummy tournament.
Certainly, with a notoriety like that it was not very long before players became shy of gambling against stu. He could find no games and in his agony he started doing something no one had done prior. He offered beginning handicaps to likely opposing players in the wish that they may play with him if they believed they held an advantage. He deliberately played from a bad position and one account has it that he even competed against a regular absconder. Mid match, he get a few words of wisdom that the bad egg was at it one more time but Stu Ungar guaranteed that he knew of the cheating and he would still win, which he did, of course.
The same trend followed Stu Ungar into sin city. He won so frequently that the casinos started asking him not to gamble in their poker rooms anymore. The reason for it was that other poker room visitors would not sit at the table if Stu was seated.
Stu Ungar is recollected more for his accomplishments in holdem poker but he always said that he was far more skilled at gin rummy.
He beat Doyle Brunson in the World Series of Poker in 1980 and became the youngest world champion. Because of his looks that made him seem far younger than he actually was, he was nicknamed, "The Kid".