Donald Trump managed to be elected president both without the benefit of political expertise and in spite of it. Trump’s campaign team was ad hoc, separate from the Republican establishment (and therefore embracing your Paul Manaforts and your Carter Pages) and ultimately managed by the guy at the top, whose experience in politics largely consisted of calling in to “Fox and Friends” every Monday. He was told he had to change to win, he was told he couldn’t win, he was told that everything he was doing was wrong.

But he won. Trump’s confidence in his own political instincts and his rejection of expertise was validated. And so he entered the White House with a reinforced sense that he knew better than those who would tell him differently. In short order, that sensibility appears to have permeated Trump’s Washington.

There are 2.8 million people who work for the federal government, a number that includes postal workers and people at national parks and myriad bureaucrats tucked away in buildings around D.C. It also includes a lot of people whose jobs — and careers — are predicated on knowing a lot about very specific things: foreign countries or the weather or how the economy moves around.

Since Jan. 20, 2017, that expertise has consistently been discounted. It was before the election, too, when Trump would disparage jobs numbers as “fake” because they suggested an economy doing better than he wanted to present. And there have certainly been times that government expertise has failed, as Trump noted when he pointed to failed analysis in Iraq to discount intelligence agencies’ evaluations of Russian meddling. But the government employs a lot of people who know a lot about a lot of things and, even if they don’t have answers to questions at the ready, often know how to find those answers.

When those answers aren’t helpful, though, the Trump administration often doesn’t embrace them.

Last week we learned that the Department of Labor buried a report showing that a proposed rule on tipping would lead to billions in gratuities transferring from employees to employer.

“Senior department political officials — faced with a government analysis showing that workers could lose billions of dollars in tips as a result of the proposal — ordered staff to revise the data methodology to lessen the expected impact,” Bloomberg reported. “Although later calculations showed progressively reduced tip losses, Labor Secretary Alexander Acosta and his team are said to have still been uncomfortable with including the data in the proposal.”

This mirrors a move reportedly made by White House adviser Stephen Miller. Asked to assess the effects of refugees on the United States, the Department of Health and Human Services determined that they’d added a net $63 billion to the economy over the past decade. This wasn’t the point the White House was hoping to make, so the report was never made public.

At the Environmental Protection Agency, Administrator Scott Pruitt took an active hand in scrubbing the EPA website of references to and information about climate change. At the Treasury Department, Secretary Steven Mnuchin came under fire after a promised report showing that the economy would grow under the Trump tax plan never emerged, prompting an investigation by the department’s inspector general. Finally, the department released a one-page summary that didn’t make the case that Mnuchin promised.

Politico reported on Tuesday that Trump’s efforts to combat the opioid crisis have been reshaped since adviser Kellyanne Conway took over the role.

Conway, Brianna Ehley and Sarah Karlin-Smith write, is “quietly freezing out drug policy professionals and relying instead on political staff to address a lethal crisis claiming about 175 lives a day. The main response so far has been to call for a border wall and to promise a ‘just say no’ campaign.”

Trump is also expected to propose sharp cuts to the Office of National Drug Control Policy, a department that currently has no head. Recently, a 24-year-old with no relevant experience was serving as deputy chief of staff to the department, until The Post noted that his short résumé — he graduated from college in May 2016 — also contained factual inconsistencies.

The administration is elsewhere shedding experienced staff. At the State Department, for example, experienced diplomats have been departing at what the head of the American Foreign Service Association called “dizzying” speed. As of this writing, there is only one career ambassador left at State, down from five when Trump took office. This is in part an effect of Secretary Rex Tillerson’s deliberate goal of dramatically shrinking the diplomatic agency, though the net effect is that experienced government officials are looking for new work.

Trump’s preference for loyal amateurs over politically ambivalent experts was obvious when he started naming Cabinet officials. Rick Perry was tapped for the Department of Energy despite not understanding what the agency did.

The Post’s Ben Terris this week profiled Ben Carson, retired neurosurgeon-turned-Cabinet-secretary. Carson’s lack of familiarity with the agency he runs is seen by some there as a quiet blessing.

“While other Cabinet-level appointees have the will and knowledge to unravel the administrative state — Scott Pruitt at the Environmental Protection Agency or Ryan Zinke at Interior,” Terris writes, “it’s unclear if Carson really knows how to find the various self-destruct levers, or if he’d even want to pull them.”

Government employees are by no means infallible and in no sense immune to the biases that affect any of us. Many are, however, much more knowledgeable about various subject matters than any newcomer could hope to be within even a year of getting to the nation’s capital. One of the successes of the American experiment has been that consistent cadre of employees who serve regardless of president and use their expertise to help steer the country.

Under Trump, it seems that they’re often just more experts, more “swamp” to be brushed aside as an impediment to what his gut — or his team’s guts — tell them is the right thing to do. Trump’s gut got him a majority of electoral votes. It did not get him a majority of actual votes or a majority of the country approving of the job he’s doing as president.

Others might take from that a lesson in humility, not validation.