It was nine and a half hours after the businessman Denis O’Brien announced his exit from Communicorp, the radio station group he founded 32 years ago. Wearing circular glasses and a black jumper O’Brien was holding forth to a group of students during an online question and answer session with the Dublin Business and Economics Society in Trinity College Dublin. A question is asked if O’Brien will miss being in the media. “No. I will miss the people I worked with over the years in the media, sorry Communicorp, because we had great relationships,” O’Brien said. “But you know I…