A knack for blackjack turned Arnold Donald into a cruise-goer in his 20s. He had heard ship casinos didn’t shuffle their decks all that much, making it possible to count cards. His winnings, he says, often paid for much of the vacation.
Taking the helm of Carnival Corp. in 2013 was more of a gamble. The year before, Carnival’s Costa Concordia capsized off the Italian coast, killing 32 people. Then in early 2013, an engine-room fire aboard the Carnival Triumph sparked another crisis, leaving more than 3,000 passengers to contend...