The fledgling president, ridiculed for his inexperience during the recent campaign, had just suffered a stunning setback less than 100 days after taking office. He ruefully admitted afterward, “No one knows how tough this job is until he has been in it a few months.”

Talking with a friend, the embarrassed president raged over his gullibility in accepting the advice of his top advisers. As he put it, “I sat around that day and all these fellas all saying, ‘This is going to work.’ … Now, in retrospect, I know they didn’t have any intention of giving me the straight word on this thing.”

Then, as recounted by biographer Richard Reeves, the president added with renewed determination, “Well, from now on, it’s John Kennedy who makes the decisions as to whether or not we’re going to do these things.”

No, Donald Trump, you’re no Jack Kennedy.

But for any president confronted with failure, there are enduring lessons in the way that JFK responded to the April 1961 Bay of Pigs debacle. Even now, more than a half-century later, it is stunning how CIA bungling led to the deaths of 100 Cuban exiles and the capture of 1,200 of their compatriots just two days after they had invaded Cuba in an attempt to spark a revolt against Fidel Castro.

At a press conference afterward, Kennedy directly acknowledged his culpability: “There’s an old saying that victory has a hundred fathers and defeat is an orphan. … I am the responsible officer of this government.”

But Kennedy tried to understand his failure as he consulted with his five-star predecessor Dwight Eisenhower at Camp David and asked retired Gen. Maxwell Taylor to help direct an internal inquiry.

The president also informed legendary CIA Director Allen Dulles and his deputy Richard Bissell that they would have to step down. As Kennedy explained to Bissell, “In a parliamentary system, I would resign. In our system, the president doesn’t and can’t. So you and Allen must go.”

The collapse of Trumpcare is, of course, a far cry from an ill-planned covert military operation. But it is telling that Trump’s response to the failed late-January raid in Yemen that killed a Navy SEAL was similar to his reaction when his health care bill went down in the House. In both cases, the president insisted that the buck had no business stopping anywhere near the Oval Office.

The thought of Trump modifying his approach to the presidency after his doomed “repeal and replace” health care crusade brings to mind the old joke about how many psychiatrists it takes to change a light bulb. The answer: One, but the light bulb has to want to change.

Barring a Mike Pence, Steve Bannon and Ivanka intervention, it is a safe bet that Trump will never change. Whenever the president is cornered by reality, he retreats to his two favorite defenses, both prominently displayed in his Time magazine interview last week with Michael Scherer.

Trump revels in reminding the world that he pulled off the biggest November upset in nearly 70 years. As he told Time, “When everybody said I wasn’t going to win the election, I said, well, I think I would.” Trump’s other defense is always his crowds of true believers: “I went to Kentucky. … We had 25,000 people in a massive basketball arena. There wasn’t a seat, they had to send away people.”

Outsiders, of course, prefer to trust measures like Trump’s ever-shrinking approval ratings that now regularly dip below the 40 percent mark. Even Jimmy Carter maintained an approval rating well above 50 percent during the entire first year of his star-crossed presidency.

But in the White House, there remains the steadfast belief that Trump is reinventing the rules of politics. It’s almost as if the president could shoot someone on Fifth Avenue plus have his approval rating fall into the single digits — and still be re-elected.

All this leads to the conviction in Trump World that there is an artful strategy embedded in the president’s seemingly wild improvisations. Every occupant of the Oval Office has had his acolytes. Still, it is hard to recall a president who combines the demand for blind loyalty with such an impervious refusal to accept something called reality.

The talk coming from the White House in the last few days suggests that the president is prepared to reverse field to work with the Democrats on infrastructure, the budget and taxes. Unmoored from anything resembling fixed principle, Trump may find it easy to assume that others in politics are as malleable as he is.

What will likely prevent the Democrats from helping Trump are indelible memories of president’s prior indefensible behavior. It’s not just that Trump has described Barack Obama in tweets as a “bad (or sick) guy” and being the equal of “Nixon/Watergate.” Or that Trump has never silenced the “lock her up” chants at his recent rallies directed at Hillary Clinton.

Most Democrats also find it difficult to forget the wanton cruelty — coupled with staggering incompetence — of Trump’s initial immigration order. The emotional airport scenes and the wrenching stories of families being separated are not memories that can be airbrushed away like changing the blueprints for a new hotel. This helps explain why in a recent Economist/YouGov Poll only 7 percent of 2016 Clinton voters have a favorable impression of Trump.

There are no do-overs for a president. All you can do is to learn from your earlier mistakes as John Kennedy did during the 1962 Cuban Missile Crisis. But as long as Trump remains defiantly unapologetic and stubbornly nonreflective, the only thing he is likely to discover — again and again — is the staggering difficulty of the job.