The Saudi ambassador to the United States from 1983-2005 was Prince Bandar. Because he is the son of a part black slave girl, he's ineligible for the Saudi throne, but he has been an invaluable servant of the royal family at tirelessly spending its (not) hard-earned money to buy the maximum influence in the global imperial capital. For example, when George W. Bush thought about running for the White House, George H.W. Bush asked Bandar to educate his provincial son on America's foreign policy.
Who knows what fraction of Official Washington he's gladhanded or outright bribed? Do you, for example, really want to be at the sold-out Redskins-Cowboy game? It just so happens that Bandar is a close, close friend of Cowboys owner Jerry Jones. Bandar's memoirs would make interesting reading, although he no doubt he has his notes about everybody he's dealt with in his long career locked tightly away (but perhaps not so tightly locked up that he hasn't rigged some kind of deadman switch that would publish them in case of something unfortunate happening to him ... just speculating ...)
Every so often, however, Bandar tends to disappear, either due to alcoholism or depression or who knows what. He is said to have had his first depressive disappearance in the mid-1990s. He seemingly disappeared off the face of the earth from 2008 to 2010, but how now he appears to be back with a vengeance, running Saudi Arabia's adventure in Syria.
Much of history is made by men whose manic phases happen to coincide with eras of opportunity.
One question I've never seen investigated is whether bipolar disease might be semi-adaptive in a few lucky individuals. Do cycles just hit at random, or in some people do they coincide with auspicious and unauspicious periods? Perhaps we'll never know because if you fall in the latter category, they don't call you crazy, they call you "Mr. Speaker" (or whatever maximal title you attained during an up period).