Tragedy is the word that comes to mind. After all "Oedipus Rex" by Sophocles, which defines tragedy, is a dramatic narrative of a once powerful, successful, and loved king whose life truly becomes a tragedy.
Since the story of Oedipus, there have been many a powerful man who has committed hamartia, or a tragic mistake as Aristotle defines it in his Poetics. Upon an examination of political and military figures, often one discovers this "tragic mistake."
Certainly, Richard Nixon is an example of a powerful and successful man who committed tragic mistakes. Ahead in the polls by eleven points in September of 1960, just two months before the election, Nixon refused to put on TV makeup even though he had been recently ill. When the cameras recorded his close-ups, his "5 o'clock shadow" showed, he appeared pale, and perspiration on his upper lip from his slight temperature made him appear ill at ease. A tragic mistake of not ensuring that he would look his best cost Nixon the debates and arguably the election against the handsome, cool John F. Kennedy.
Having lost to Kennedy in 1960 and having narrowly beat Hubert Humphrey in 1968, Nixon became somewhat paranoid in his campaign for re-election in 1972 despite having had a successful first four years as president. So, he committed his tragic mistake of bugging the Democratic headquarters in the Watergate hotel.
Other presidents, of course, have had their tragic flaws such as Jimmy Carter whose tragic flaw during his administration was his extreme weakness. His tragic mistake was in not supporting the Shah of Iran, a decision which led to the creation of the theocracy of Iran that is to this day a problem for the U.S. Carter's flaw was that he did not understand that one cannot be a total humanitarian and protect one's nation. His inability to resolve the hostage crisis in Iran after the Shah was disposed was a political debacle and embarrassment to America.
In Reagan's administration, desiring to destroy communism, he went around the wishes of a Democratic Congress which would not fund the sale of arms to the Nicauraguan contras who tried to fight communism. This scandal implicated numerous members of the Reagan administration as well as the president himself as he denied knoeledge of details of any transactions.
Your question is under the heading of "Deep Politics and the Death of JFK," so I assume you are wanting a topic in the area of famous politicians. One topic that is very relevant at this time in history is "Why do political leaders find themselves in sexually compromising scandal?
In the past year there have been over 11 incidences of politicians who seemingly have everything going for them but they got caught with a prostitute, in an affair, or some sexually compromising situation.
The first one that comes to mind is John Edwards. He was running for President and during the primaries it was discovered he was having an affair. There is even an allegation that he has a child with this mistress. It has taken the reputation of the "golden boy" and ruined his chances of ever being President of the United States.
Another politician is former Gov. Rod Blagojevich who is being tried for corruption in the state of Illinois. He is being charged for trying to "sell" the Senate seat vacated by President Obama. His famous career is over.
Outside of the political area is obviously Michael Jackson who's fall from the fame and stardom eventually caused his death. Any of these people would make a great report.
"If a candidate chooses the short-term pleasures offered by adulterous flings over the faithfulness, discipline, and plain hard work that reap the long-term reward of a great marriage, will he then also choose public policies that offer quick fixes, with little or no regard for their long-term consequences?"