Bud Light’s marketing blunder is changing the beer industry landscape. According to “Shark Tank” star Kevin O’Leary, the impact is so unprecedented that he’s pumped to teach the case to business school students. “It’s such an incredible story that it’s becoming what’s called a chestnut case in business schools,” O’Leary said in a recent interview with Fox Business. “Beer is a commodity, the only thing of value is the brand you spent hundreds of millions creating and then to actually lose 25% mar