Who is going to stick with Trump?

I believe it's now impossible to work for Trump and do your job properly. Sarah Sanders, press secretary, does her best but she must be as exasperated as anyone in the White House. On behaf of her boss she has to come up with some sort of clarifying explanation for why Trump says this or that and then in very short order is saying something else. "Oh God, not again" must be her most often uttered private comment. But the greatest burden of responsibility for Trump's wayward comments and contradictory policy statements lies with four men: General Jim Mattis at the Pentagon, John Bolton as national security adviser, Mike Pompeo, secretary of state and, of course the long-suffering General John Kelly as chief of staff. It doesn't really matter what they advise because if Trump has decided not to be advised on a particular issue he'll do what the hell he likes. As president I guess he is within his rights to ignore everyone and go in the opposite direction to everyone else. But surely somewhere in the constitution laid down by the founding fathers there must be a clause which says the president at all times must act in accordance with the best interests of the United States, or something like that. When I spoke to a former US official who served under Obama he said that Trump only listened if the answer he got was what suited his own end. He said Trump was all for himself. That's a pretty frightening judgment, albeit coming from someone who served a very different type of president. Will Mattis, Bolton, Pompeo and Kelly be strong enough and clever enough to steer Trump in a direction that will benefit the US and the rest of the world, or will they give up and leave the near-impossible job for other people? And even if they stay, Trump is almost bound to get bored with them if they fail to do exactly what he wants, or if they fail to achieve his top priority objectives, such as a totally denuclearised North Korea. That's a great objective, no question, but if Pompeo fails to deliver, how much longer will he survive before Trump turns to someone else?