In the show’s final decade, Oprah and her team staged massive spectacles of increasing grandiosity, from the infamous car giveaway to a 21,000-person flash mob that shut down part of Chicago.  “It had become increasingly more difficult to top what you’d done the year before,” Oprah told WBEZ’s Jenn White. “I mean, to the point where we literally sat in a room saying ‘What about outer space?’ ”  That’s what we look at now: Oprah living her life at the top, pushing the boundaries of what could be done with the world’s most powerful talk show, and why it all had to end after 25 years.