I have said many times that President Trump wants to run the White House as though it is Trump Tower, and he still fails to grasp the myriad differences between business and politics.
As a businessman, Trump can fire at will, and has probably done so in a fit of pique at someone who displeases him.
He fails to grasp that doing so in political circles has consequences, because for the first time in his adult life, he has to account for his decisions, and answer to other people for them.
Trump understands opposition, he does not deal with dissent - something he shares with Margaret Thatcher in her last years.
The difference is, Thatcher understood on a fundamental level that in politics, pragmatism is everything, as is playing the long game, and until the end of he career, she would accept dissent on the basis that the dissenter may well have a valid contribution in other areas.
Trump uses sackings like a small child - the equivalent of picking up his ball and going home, as this apparently spiteful action underlines.
You need to think and behave like a grown-up to be a politician, yet another thing President Trump cannot understand.