Marisa Mayer’s tenure as chief executive of Yahoo has not gone well. Ad revenue has dwindled. High-profile acquisitions have failed. Users’ personal info was breached — twice. Now, Verizon is set to acquire Yahoo for a fraction of its worth a decade ago.  And in a few months, Meyer faces her punishment, as dictated by the free market: walking away with $186 million. Reports the New York Times: “All told, her time at Yahoo will have netted her well over $200 million.”

“Government should be run like a business,” goes the quasi-proverb. In years past, Meyer’s golden parachute would be this month’s best evidence of why that supposed maxim makes little sense. But now that proof sits in the Oval Office. As Donald Trump’s presidency reaches 100 days, we are seeing firsthand the results of a government run like a business, and the results are not pretty.

From early in Trump’s business career, there has been a consistent verdict: The 45th president is driven by impulse and the short term. Tony Schwartz, the ghostwriter of “The Art of the Deal,” won Trump’s admiration with a 1985 article that described him (in the New Yorker’s words) as a “ham-fisted thug.” Whether it be Trump Steaks, Trump Vodka or numerous other failures, Trump has consistently bought into ventures brought to him because of the exposure in the short term, regardless of the viability in the long term.

Now that approach has been brought to the White House. As The Post reported Thursday, the president “often seems more interested in short-term accomplishments — and positive cable news headlines — than longer-term policy goals.” This explains why Trump has been so uncompromising on executive orders — where he does not have to deal with anyone else — and so yielding on legislative and diplomatic negotiations. Just this month, he has caved to Democrats on health care, China on currency manipulation, and Canada and Mexico on the North American Free Trade Agreement. What’s important is not the long-term policy outcome but the near-term impression of success.

Many will want to ascribe this short-term, impulsive thinking to Trump alone. The truth, however, is that corporate America rewards this approach. We see this in the “stock price first” approach of big corporations, which values higher prices and bigger dividends over investment in the company’s future. In the long run, that hurts Americans as a whole, as investment in infrastructure, innovation and other improvements is lost.

But let us return to Trump. Now he has a tax “plan.” I say “plan” because the administration has put forward only bullet points, with many specifics missing. There are no budget projections, no economic projections and no clear strategy on how the “plan” will get through Congress. (Treasury Secretary Steven Mnuchin said the administration would consider both working with Democrats and ramming the bill through on party lines.)

Pushing this “plan” through Congress will mean making deals, whether that be with Republicans concerned about the impact on the deficit, interest groups that object to eliminating specific deductions or Democrats concerned about, well, almost everything. But that doesn’t concern Trump. What he cares about is the image: As The Post reported, the president is “desperate to notch tangible victories.” What his tax proposal does to the deficit or — far more importantly — inequality is of little concern. The details don’t matter so long as something gets done for him to show off.

Obviously, this is no way to run a country. The New Deal, the moon landing and the Constitution itself were not created with short-term returns in mind. America’s success is not measured in returns to investors. Among the many myths that Trump’s presidency will hopefully dispel, “government should be run like a business” should be the first to die.