President Trump is not a politician, that’s why. Also he knew not, just how bad the swamp really is. He’s a fast learner though, plus he needed time for them to expose themselves.
“plus he needed time for them to expose themselves.”
That’s the point: He should have fired them wholesale, not “wait for them to expose themselves”. That’s when it would be too late. It doesn’t take a politician to know this. Any executive knows not to keep prior executive staff due to misplaced loyalties.