The global financial markets are not in crisis. Though some pundits stoked panic with their coverage of several days of market plunges before Tuesday’s leap, stock prices are still near their record highs, the economy is creating jobs and many workers are finally getting decent raises after years of stagnant wages.

Which doesn’t mean that there’s nothing to worry about. In recent months, time after time, both the current administration and its allies in Congress have called into question their credibility and competence to manage the economy or handle a financial crisis if one were to occur. President Trump has repeatedly patted himself on the back for a surging stock market, seemingly unaware that stocks can go down, not just up. His Treasury Department in December released a one-page analysis that made outlandish economic assumptions to justify giant tax cuts for corporations and wealthy families. Republican lawmakers in Congress went even further, attacking the Congressional Budget Office and Congress’s Joint Committee on Taxation, both nonpartisan, because those analysts had the temerity to warn that the tax law would add to the federal deficit.

Mr. Trump wants everyone to know that his election delivered a booster shot to the economy and stocks. “The reason our stock market is so successful is because of me,” he told reporters in November. Truth is, the president was just lucky enough to have inherited a growing economy and a rising stock market. Though his tax cuts were an expensive gift to investors, he has not been in office long enough to have fundamentally changed that trajectory. But his erratic behavior and poor policy choices are clearly worrying the majority of Americans who disapprove of the president.

One reason some investors have become nervous recently is they fear that the tax cuts, which Mr. Trump and Republican lawmakers sold as a way to stimulate the economy, could end up hurting the economy in the not so distant future. The tax law and a push by the Trump administration to increase military spending will reduce federal revenue and force the Treasury to borrow more money when the economy is close to full employment. This could stoke inflation and prompt the Federal Reserve to tighten monetary policy. That, in turn, would slow the economy.