Not "incorrect" jfc. They made their money from card-counting at Blackjack until the 1990s.
This is from Richard Flanagan's profile on David Walsh in the New Yorker in 2013.
And so Walsh ended up in his first and, as it happened, his last year at the University of Tasmania, getting about in zip-up wool cardigans that his mother knitted for him, studying mathematics and computing. One day in the Physics Club, he overheard a conversation about card counting.
Six years earlier, Tasmania had opened Australia’s first legal casino, a five-minute walk from the University of Tasmania’s mathematics department. The students in the Physics Club had read a book on card counting, and started using what is known as “basic strategy”—principles based on mathematical calculations—to play blackjack at the casino. They were betting four dollars a hand and winning six dollars an hour.
“Why not scale up?” Walsh asked.
“Who’d take that sort of risk?” one of them replied.
Walsh taught himself basic strategy, walked down to the casino, and began winning. One afternoon at the university bar, playing a video game by himself, he was approached by a student he knew only vaguely.
“Apparently, you’re the bloke to get gambling calculations done,” Zeljko Ranogajec said.
For the other student card counters, Walsh said, gambling at the casino was “a social thing. For Zeljko, it was serious.” Walsh burned his money, but Ranogajec, a law and commerce student and the son of Croatian immigrants, hung onto his winnings, using them to bet ever bigger. Ranogajec understood the need for a mathematical edge if they were to win, while Walsh could appreciate the virtues of Ranogajec’s approach. And so they joined forces. By the end of the year, Walsh was at the casino every day from when it opened, at one o’clock in the afternoon, to four in the morning, when it closed. The dealers laughed at the students for thinking they could win, but Ranogajec’s pool was growing rapidly: from a two-hundred-dollar stake to fourteen thousand dollars in twelve months, and then to a hundred and fifty thousand dollars a year later.
In 1985, Ranogajec took Walsh with him to Las Vegas. They lost almost everything they had. Ranogajec spent the next five months at the tables painstakingly winning back their stake while Walsh escaped what he called “the scream of the bland” for a new discovery which was to prove their big break: the world’s largest collection of gambling literature, housed at the library at the University of Nevada. He read widely and deeply on gambling history and gambling systems, the psychology of gambling, its management, its workings as a business, why people win and lose.
When they returned to Australia, Walsh, who had never liked playing blackjack, began writing a computer program to bet on horse racing. Walsh, Ranogajec, and Ranogajec’s girlfriend took the overnight ferry to mainland Australia and drove on to Sydney, Ranogajec singing “If I Were a Rich Man” over and over. On Australia Day, 1987, the two young Tasmanians placed their first bet on a horse race using Walsh’s program. They won.
Ultimately, Thoroughbred racing became the main focus of their gambling, but for a time they struggled. Their ideas, systems, and programs were good, but not good enough. They were making only a little money and spending a lot, and on occasion they came close to losing it all. They kept going by playing blackjack. They were by now formidable players, and their ongoing wins led to them being banned from all the Australian casinos, so they took to playing in Korea, Sri Lanka, Macau, and South Africa to stay afloat. But the Bank Roll was becoming too well known. The group trained new faces in its card-counting system and sent them out to play. But the new card-counters were in turn quickly identified and banned.
Walsh and Ranogajec diversified. Using high mathematics and low cunning, they identified where small profits could be made by betting large sums. Risk remained. In 1993, Ranogajec won an eleven-million-dollar jackpot in a Sydney club, but he had bet fourteen million to win it. They went from racetrack to dog track to gaming table and back, playing everything in between, from chocolate wheels to baccarat; from Thoroughbred to greyhound racing.
There was also what Ranogajec calls “the low-lying fruit.” One time, they paid hundreds of people to fill out entry forms with every possible permutation of a lotto game, and won $1.6 million. Another time, Walsh discovered that a particular model of roulette wheel had an inbuilt and undetected bias that led to the number 27 being twenty per cent more likely to win, and win they did. Walsh bought himself a new Mercedes with the vanity plate RED-27.