He lost his job before he even started, which comes as no surprise to anyone who has spent any time working in Washington. Which, of course, the president’s choice for communications director had not.

The story of Anthony Scaramucci should be a cautionary tale for the Trump presidency, but there is no indication that Donald Trump has any intention of learning from his nonstop mistakes.

The Mooch had to go precisely because he was Trump’s Mini-me. He brought to the job the same combination of arrogance and ignorance that the president displays. The difference is, the president can’t be fired — except jointly by the House and Senate.

But as Mr. Mooch learned, the president is the only person in the administration who can’t be fired.

Everyone else (with the exception of Robert Mueller) — especially those who are not related by blood or marriage — is always fair game in Washington. It’s called damage control. If he had asked, any intern could have told him that.

But the Mooch asked no one.

According to his soon-to-be ex-wife, he’d spent every minute since January (when he sold his company, expecting to go right to the White House) trying to get even with Reince Priebus, who he was convinced had blocked his appointment (certainly one of Priebus’ best moves, if true), and to ingratiate himself with President Trump.

And he thought he had succeeded, poor, stupid SOB.

It was both arrogance and ignorance on display when the Mooch — furious over reports of Trump’s intimate dinner with Fox News stars Sean Hannity and Kimberly Guilfoyle, former Fox News executive Bill Shine (whom the Mooch was reportedly planning to hire) and Scaramucci himself — decided to unload in language never before printed in a family newspaper.

The language was so vile it’s easy to forget what he actually said: which was that he was going to fire everybody, starting with Reince Priebus.

This joker didn’t even realize that no new chief of staff would ever put up with him, much less his reporting directly to the president.

The Mooch was so determined to get his vengeance on Priebus, and so ignorant as to how Washington and the White House work, he didn’t realize Priebus was his only chance of survival.

Once he was gone, Mooch’s days were numbered — with very low numbers.

And so it was that after reportedly encouraging the Mooch’s vile rant, after Mooch-man thought he’d landed on his feet and could do no wrong, the president supposedly talked to family and friends over the weekend and they told him it did not help his agenda to have a foul-mouthed gazillionaire threatening to take over the White House in language most Americans would never allow their children to use.

Not to mention the fact that no new chief of staff in his right mind, and certainly no retired general, would ever allow a guy with a big mouth, no filters, no judgment and no sense of restraint to run free in the White House threatening members of the staff and reporting directly to the president.

Had the Mooch spent any time in Washington, had he known anything about politics or government, he would have kept his mouth shut, at least until his starting date, and never called a reporter to rant, on the record, in vile language.

Exactly who did he think he was? The @realdonaldtrump? Wrong.

If the Mooch was surprised, it was only one more sign of the dangerous mixture of arrogance and ignorance that got him hired by Trump and fired by Gen. John Kelly on his first morning of work.

The problem, of course, is that Mooch is not the only one in the White House who displays that peculiarly dangerous and unattractive pair of qualities. As the Greeks used to say, “The fish rots from the head.”

For all his talents, it’s not clear what Gen. Kelly can do to restrain the fish head from continuing to lose face almost as fast as the Mooch.

Susan Estrich is a best-selling author, the Robert Kingsley Professor of Law and Political Science at the USC Law Center and was campaign manager for 1988 Democratic presidential nominee Michael Dukakis. Click here to contact her or click here to read previous columns. The opinions expressed are her own.