What surprised Wall Street — what terrifies Wall Street — was Mr. Trump’s inquiry as to whether he had the power to fire Mr. Powell, whom he appointed in February. That injection of uncertainty was then magnified when Mr. Mnuchin announced from his Mexican vacation spot that he had chatted with six big bank C.E.O.s in an attempt to assure investors that there was adequate liquidity in the financial system. Anyone who experienced the Great Recession might recall that merely raising the idea that there might not be adequate liquidity immediately injects doubt into investors’ minds about adequate liquidity, whatever assurances you attach afterward. The Dow promptly had its worst Christmas Eve trading day ever, disgorging 653 points, or 2.9 percent. After a slow start on Wednesday, major market indexes roared back, with the Dow climbing more than 1,000 points, or almost 5 percent.

Mr. Trump was in Iraq, and off Twitter, on Wednesday.

Mr. Trump is King Minus. Everything he touches turns to lead. And everyone else is at fault but him. He can’t understand it. Didn’t he give Mexico and Canada a great deal in replacing Nafta with Naft2? He thinks so, even though the Canadians fought furiously until they got an agreement they could live with; the Mexicans are still on the fence, if you’ll pardon the pun.

And didn’t he win the trade war with China? The president brays that jobs will be moving here from there, which will make the trade deficit diminish. The reality is that the trade deficit continues to climb, mostly because it helps our economy. What is diminishing instead are sales of soybeans to China, once the largest customer for American farmers. In November, China bought exactly zero soybeans from us. Merry Christmas, Iowa. Does this feel like winning?

In Mr. Trump’s snow-globe reality, our days are merry and bright as long as he’s in charge. It’s only when those other fools interfere — the courts, the Fed, Congress, whoever is chief of staff — that things go wrong. Thus the government shutdown that he bragged he would own he now says belongs to the Democrats. No one is buying that one, not even in his own party. And no one is buying his $5 billion Mexico wall, either. And that includes the Mexicans. Nor should they. The number of people entering the United States from Mexico has been declining for a decade, but Mr. Trump has now wasted hundreds of millions of taxpayer dollars placing American troops in Texas to protect us from an immigration threat that doesn’t exist.

While a paralyzed federal government is not yet damaging the economy, the damage from Mr. Trump’s other personal policy perversions is piling up. On its own, the economy, while clearly slowing, is doing well enough and will probably continue to do well enough with minimal fine tuning. Mr. Trump complains bitterly that Mr. Powell is going to turn him into Herbert Hoover by doing what the Fed is mandated to do. But what turned Hoover into Hoover is a Federal Reserve that did nothing and a Republican Congress that conducted a disastrous trade policy rife with tariffs.