Imagine living in a bubble so impermeable, it didn’t occur to you that retailing a photograph of a decapitated president’s head would be a horrendous career move — a bubble in which you don’t know anyone who doesn’t think the world would be a better place once Donald Trump had had his head cut off.

That is the world Kathy Griffin lives in.

This Times Square Rolex knockoff of Joan Rivers knew the photograph of her holding the decapitated and bloody head of the president of the United States was edgy and provocative.

That’s why she was excited to pose for it. That’s why she sent it to TMZ. That’s why she initially defended the picture to the journalist Yashar Ali by claiming it was “art.”

But in her heart of hearts, Kathy Griffin is no more a provocateur than Tickle-Me Elmo. Her professional life has been about making fun of people who try and fail to achieve genuinely deserved American celebrity. That’s very nearly the opposite of risky. Making fun of a Kardashian is about as daring as smoking a clove cigarette.

And that’s why it only took her two hours to realize she had done something disastrously self-destructive — and to try to salvage her career by disowning what she had done.

Usually there’s a cycle in these controversies. First, the controversialist responds with obnoxious contempt to those who are shocked. Second, as the number of enraged tweets begins to rise into the thousands, the contempt turns to anger as the controversialist believes she’s being defamed.

Then, as it becomes clear to the controversialist that she crossed a line she shouldn’t have crossed, she says she is sorry if she offended anybody and deletes the offense from social media.

Griffin didn’t go through these stages. No, in incredibly short order, she posted a video in which she looked even more terrified than the martyred ISIS hostages whose deaths she had just mocked so repulsively. In that video, she issued an apology whose abjectness belied its candor. She surrendered any pretense of being an “artist” making a statement and basically begged the world not to punish her for her misdeed.

Griffin only knew she had done wrong because of the swiftness with which the nation passed its judgment on her disgusting stunt. For like all fame-hungry performers, in the end, what she wants most of all is love — and she thought she would get more love for posing for and posting that photograph.

Why would she think this? In the bubble in which she lives, in the world in which she travels, in the frame of reference in which she nestles like a baby nestling in a Moses basket, it must have seemed to Kathy Griffin that there could be no way she could go too far if the object of her unspeakable provocation was Donald Trump.

In fact, she must have believed, the further she would be willing to go, the more praise her action would be likely to engender.

That was not an unreasonable belief. Stephen Colbert took to the CBS airwaves and used a word to describe Trump that would have gotten him fired had he used it about Barack Obama — only he would never have used such a word about Barack Obama. His show’s ratings have only continued to surge in the wake of it. What would your takeaway be from that if you were Kathy Griffin? You might take one look at the cover of Village Magazine’s February issue, in which Trump appears in the cross hairs of a rifle sight, and figure it got a lot of attention for that, so imagine how much more attention I might get for this.

Griffin probably figured others had crossed the line before her, so she wasn’t really crossing a line at all. Or maybe she figured where Trump is concerned, there is no line.

Oh, sure, the yahoos would scream, but such screams would surely sound like a thousand angels singing to Kathy’s friends and employers. Their agony would only be a sign her stunt had truly hit home.

Yes, what could be more wonderfully easy and satisfying than to be provocative when you think the only people you will truly provoke are the people you and your community of like-minded showbiz progressives despise!

When Griffin realized it was horror rather than “you go girl” admiration she had provoked, and not just among the yahoos but with everybody with a soul enough to understand she was normalizing an image of a presidential assassination, she tossed the photograph onto the trash heap of history.

She threw herself on the mercy of the court of public opinion in hopes of sparing the mediocre career she has so painstakingly constructed by playing the part of a sharp-tongued, take-no-prisoners truth-teller. No luck. In 24 hours’ time, she had lost her annual gig co-hosting the CNN New Year’s Eve special.

The taste of her own medicine must be especially galling to Kathy Griffin today.