I believe he thought there were people he could trust in the corridors of power. He was wrong.
Actually he was unprepared to take over. He relied on the supposed good intentions of the bureaucracy which immediately went into resistance mode. That does not even begin to touch the overt attempt to get him out, the Russia Hoax. I am surprised he was able to do what he did by sheer force of will. I will never forget that f in piece of S Ryan who did all he could to undermine anything he did from the Congress which the GOP had in control plus the Senate. Alas, nothing we can do now, well almost nothing but few what to go there.