Well, post-impeachment, the anti-Trumpists are seriously low on ammunition. They’re reduced to shooting spit-balls (tin foil hat aside). But still, if he just replaced all of them on Day 1, what’s the worst that could have happened? A bogus impeachment? Seems kind of inevitable.
Early on, Trump made the mistake of trusting the GOP.
Who is that? Oh yeah...the never Trumper who used to be Speaker of the House! He actively tried to torpedo PT, again and again.
Some more names from Memory Lane...McCain...Flake...Graham.
DC regarded PT as an invader. If not actively never Trump, passively. But hostile nonetheless.
Candidates for posts declined, because they were told that if they worked for PT, they would never work again.
This is the environment on Inauguration Day 2017. More often than not, non-swamp administrations have to hire from the private sector. Those you want the most (because they are aware of the swamp) are least likely to take a government job (because they are aware of the swamp.) It's comparatively easy to hire for the swamp. They know each other. Government is their career...and for the left, the political is the personal.
PT didn't have anyone to staff he'd worked with before. First Christie, who was then sidelined for Pence.
So he was on his own. Not only did he not have ready replacements, the Senate told him he'd have a hard time getting replacements confirmed. Hostile Senate, including Repubs.