Do you ever wonder why every two-term president since Richard Nixon has had a scandal or three during his second term? Nixon’s Waterloo was the Watergate scandal that started during his campaign and ended with his resignation and pardon. Ronald Reagan, the next two-term president, caused the nation to suffer through the Iran-Contra Scandal where his government condemned and sanctioned Iran on one hand, and with the other sold them weapons to fight Saddam Hussein, our ally, whom we also supplied with weapons during the Iran-Iraq War. Clinton’s was Monica Lewinsky; George W. Bush’s scandals number as high as 34, according to one source. They include Abu Ghraib and no WMDs in Iraq.  Now, Obama has three scandals going all at once: Benghazi, AP and the IRS.
Three Republicans and two Democrats.  It seems scandals are nonpartisan in nature. Nixon’s scandals involved winning re-election; Reagan’s was his fierce opposition to the spread of communism, Clinton’s was sex, W. Bush’s was ignorance and arrogance, in a desire to carry out an extreme conservative agenda. Obama’s have been over the use or misuse of information to win re-election.
These second-term scandals seem to occur for one major reason: a presidential philosophy is carried to extremes, often enhanced by the pressure to win re-election.
Nixon’s philosophy was based upon his paranoia. He thought his enemies were out to get him. Unfortunately, for Nixon, this fear was partly based on truth.  His underlings associates took that paranoia and went one step farther. Nixon didn’t plan the Watergate break-in, but when his assistants carried it out, rather than revealing it to the world, Nixon covered it up.  That decision eventually would cause his resignation.
Presidential assistants Poindexter and North carried Reagan’s philosophy of hating communism to extremes. With the aid of Israel selling weapons to Iran, Reagan’s guerrilla war against the leftist Nicaraguan government could be financed, even without Congressional approval and funding. Eventually the behavior of Reagan’s aides came to light, making Reagan look either out of touch with his own administration or someone who arrogantly ignored the Constitution’s checks and balances.
Clinton’s sexual peccadilloes with Monica Lewinsky came as a result of his inability to control his sexual drives. He found, in Monica Lewinsky, a young White House intern, a willing accomplice someone who allowed Clinton to act upon his drives.
Clinton tried to cover up his adultery by lying, a major mistake in dealing with second-term scandals.
George W. Bush’s scandals came about as a result of not being willing to listen to opposing moderating opinions. His deputies, Cheney and Rumsfeld, are two examples of associates overcoming logic and common sense in the pursuit of a conservative ideal.
Obama deeply desired to win re-election. He believed, correctly in my opinion, the Supreme Court had used its power to help fellow conservatives attempt to unseat him with the Citizens United decision. Those attitudes, like a pungent odor in a room, spread throughout the entire executive branch. Combined with international events in the case of Benghazi, these fears caused some of his loyal employees to go to extremes to protect the president’s foreign affairs credentials gained by the death of Osama Bin Laden and the supposed end of Al Qaeda.
In actuality, the deaths of the four diplomats in Benghazi were the results of both State Department bungling and Congressional shortsightedness in funding embassy security. The cover-up occurred because of fear (correctly in my opinion) of the Republicans using this tragedy to destroy Obama’s chances for re-election.
In the case of the IRS scandal, some mid-level IRS employees apparently targeted Tea Party-type organizations trying to protect the president from more anti-Obama campaign spending. 
With the AP scandal, the Justice Department went after people who were leaking sensitive information, not just because of national security concerns, but more importantly to stop what the administration deemed disloyal employees who gave damaging information to the media, putting Obama’s re-election in jeopardy. 
In each of the examples above, presidents deeply held beliefs and attitudes were extrapolated and distorted to their aides and employees. Why does this occur? In all cases the blame lies as much with the opposing party. It comes from deep desire to win the election and a willingness to do just about anything to defeat the enemy the standing president and his party.   These pressures create ideal conditions for the creation of extreme actions.
Perhaps another reason comes from Lord Acton’s sage observation that power corrupts. Perhaps, additionally, the corollary is closer to the truth: power seduces its holders into overestimating their strength while ignoring the limits of power (Sourcewatch.com).
The question I am left with is, if this has been normal operating procedure since the 1970s, why haven’t standing presidents been proactive about it? Why haven’t they prepared for just such an eventuality? My guess is that many presidents do think about this trend of second terms, but they live in a pressure cooker. The pressure to not lose their re-election overrides reason.
The second term curse looks poised to continue into the future.