Why do normally responsible people in positions of high visibility and responsibility engage in career- and institution-threatening misadventures? There is no one reason. Often, however, leaders who fall spectacularly from positions of power don't work in a culture of accountability. They didn't have someone close at hand who felt comfortable forcibly pointing out the flawed behavior and the consequences to their careers and the institutions they lead.
You see this all the time with Congress, the most unaccountable organization on earth. Under the usual formula, the Congressman acquires power and enjoys perks that include kowtows, back slaps, and ring kissing from lobbyists, hacks, colleagues, and even the media—all of whom want something. So, the pol cuts himself off from reality and surrounds himself with courtiers who laugh at his witless jokes, and nod reverently when he says something ludicrous. Before long, his better judgment is gone, and he files a bill to outlaw feather dusters, or to designate the Saguaro Cactus as the state tree of Vermont.
The public expects buffoonery from politicians but not from healthcare professionals. Doctors, nurses, technicians, hospital executives are all generally held to higher standards in the communities they serve. And the vast majorities of these professionals deserve and protect that higher status with exemplary personal and professional conduct. That's why headlines about executives gone wild garner so much attention.