Tl;dr version: Kissinger was an almost superhuman ass-kisser. He had an incredible knack for playing along with whatever insane idea somebody had and made everybody in the room feel goddamned brilliant. The richest, most powerful, and most beautiful people in the world just loved being around him because he consistently sounded interesting and made them feel intelligent.
And he used that power to stay in the halls of power whoever was in charge.
The only thing that seemed his own idea was personally planning and picking bombing targets to murder hell out of everybody in Cambodia.