(CNN) - Secretary of State Mike Pompeo could barely contain himself as he stood in front of the White House press corps on Tuesday afternoon.
Hours before, national security adviser John Bolton, with whom Pompeo had repeatedly clashed, had been fired via Twitter by President Donald Trump. Pompeo had won, and he was taking a bit of a victory lap.
"There were many times Ambassador Bolton and I disagreed, that's to be sure," Pompeo said. "But that's true for lots of people with whom I interact." Later, when asked whether he was surprised by Bolton's firing, Pompeo deadpanned: "I'm never surprised."
What struck me most watching Pompeo and Treasury Secretary Steven Mnuchin live -- the briefing was scheduled to also include Bolton until Trump fired him -- was how much of a there-but-for-the-grace-of-Trump situation every single member of the President's Cabinet finds themselves in every single day.
Trump has already jettisoned nine Cabinet secretaries in less than three years. And that doesn't include his three national security advisers, six communications directors and a variety of other senior staff firings and resignations. (Trump has already gotten rid of more Cabinet officials in under three years than any president in the last 40 years, according to statistics kept by Kathryn Dunn Tenpas at Brookings.)
Trump sours on top aides faster than most people sour on their favorite song. And because his administration largely functions on his whims, you can be in the inner circle in one week and gone the next -- all because of a change in the President's mood.
Which brings me back to Pompeo. He is, without question, the current golden child of this administration. Trump plucked him from the House to be CIA director and pushed Rex Tillerson out at State to put Pompeo in that role. Pompeo has succeeded by saying and doing whatever Trump wants -- as expertly documented by the New Yorker's Susan Glasser.
But because Trump is so temperamental and changeable, channeling what he wants over some long period of time is impossible. Stick around Trump long enough and he will scapegoat you or turn on you or both. It is known.
Pompeo may find a way to get out before Trump turns on him; he continues to hint at his kind of, sort of interest in running for the open Senate seat in Kansas. If Pompeo passes on that bid, there will come a time when he is the guy on the chopping block and some other new favorite is smiling at his or her own victory.
The Point: The only constant in Trumpworld is Trump. Everyone else -- except his family -- is expendable. Everyone.