As a matter of fact, Tony would've lost even if the game had continued. However, it was obviously a trap since Luke kept the balance on his bank card a secret and proposed to end the game once he won a million dollars.
As long as Luke won just once, Tony would lose 1.4 million dollars, even if Luke didn't get blackjack, and the game would end.
Why did Luke have six hundred thousand dollars on his card? It was the remainder of the loan that he had taken out by mortgaging the villa which Takagi gave to him.
Luke had taken out an eight hundred thousand-dollar loan. He had spent more than a hundred thousand on the patent application and legal matters, and he had less than seven hundred thousand dollars left.
Without that money, it would've been difficult for Luke to win a fortune here. Chances were that he would be blacklisted by the hotels in Vegas.
