“He seems to be kind of a pathological guy.” -- Bill O’Reilly biographer Marvin Kitman.

Fox News should have fired Bill O’Reilly a long time ago.

Clearly, O'Reilly should have been ousted over his years-long reported pattern of sexual harassment, which the network spent years enabling and covering up until it was forced to take action this week.

But O'Reilly also deserved to be booted from his lofty prime-time perch for shredding any semblance of ethics in journalism.

I’m thinking specifically about two years ago, when O’Reilly was caught fabricating his resume by claiming to be have been a war correspondent who had a courageous knack for popping up at dangerous hot spots around the world where he witnessed killings firsthand.

Remember? He supposedly risked it all during the Falklands War in a “war zone.” He watched as those four American churchwomen were gunned down in El Salvador in 1981. And he nearly got killed by bricks while covering the bloody 1992 L.A. riots, and witnessed first hand the trauma of an urban civil war in Northern Ireland.

Or something.

Turns out those life-threatening “combat” claims were made up.

Like a modern-day Walter Mitty, O’Reilly just concocted the tall tales in order to make his life seem more compelling and make himself seem more accomplished. It seems the closest O’Reilly ever came to combat duty was filing dispatches from the channel’s never-ending War on Christmas.

The 2015 controversy represented a humiliating and very public undressing. But Fox News didn’t seem to care, and neither did O’Reilly. (He even lied that the media firestorm had boosted his ratings.)

“In a way, it's impossible to win a debate with O'Reilly because he is not bound by reality,” noted Mother Jones’ David Corn, who broke the story about O’Reilly’s fabrications.

And that’s been the secure bubble O’Reilly built for himself at Fox: He wasn't bound by reality and neither were his producers or viewers, which meant all bets were off.

In 2011, Glenn Beck lost his highly rated show on Fox when advertisers fled after he called President Barack Obama a racist. That was a big deal because it pulled back the curtain of invincibility and showed that the cable news ratings giant was susceptible to online activism; that boundaries of acceptable behavior could, occasionally, be applied to Fox.

Then last summer, Fox founder and architect Roger Ailes was fired after numerous women reported that the Fox chief had harassed them.  

Neither of those sackings compare to the media bombshell that went off when O’Reilly, the most-watched and highest-paid man in cable television news, was fired this week. O’Reilly’s unceremonious sacking is, hands down, the most important personnel move in Fox’s 21 years on the air.

And that’s because, in addition to being part of a seemingly systemic culture of sexual harassment at the network, O’Reilly shaped the Fox News persona. O’Reilly’s bitter, bullying, and self-pitying DNA is the same DNA that defined the channel's jerk culture for two decades.

Yes, O’Reilly’s a liar and a nativist and a bully (to guests and staffers) who has polluted the public dialogue without remorse. But what also defined O’Reilly, and what helped define Fox News for much of the last 20 years, was an ingrained sense of self-aggrandizement coupled with bottomless victimization. That became Fox’s hallmark pathology, suggesting that (wealthy) white middle-aged Christian men in America face an obstacle course full of cultural and political barriers that make life unbearable.  

It’s a feel-bad fantasy that revolves around the idea that powerful and often-unseen forces are working against Everyday Joes. And O’Reilly has led that gloomy parade as a kind of Eeyore figure, constantly bemoaning the state of affairs and most often blaming others, usually the less powerful.

That’s been O’Reilly's M.O.: self-puffery fueled by narcissism and self-pity, coupled with a deeply flawed view of his own abilities. And that’s basically been the Fox News on-air model for two decades: Be brash, make stuff up, tell guests to shut up, and smear people.

And it worked. Propelled by the impeachment of Bill Clinton, followed by the Florida recount in 2000 and the relentless on-air flag waving of the U.S.-led invasion of Iraq in 2003, O’Reilly’s ratings at Fox News soared as he and his cohorts both delivered an openly partisan take on the news and morphed into the marketing wing of the Republican Party.

O’Reilly patented the jerk model and forged a connection with his angry viewers to the point where they didn't care, for instance, if he fabricated his resume and lied to them about his “combat” reporting from years past.

He was a jerk. But he was their Irish, Long Island-born jerk. The one who told his aging white viewers that together they could stand at the barricades of cultural and political change.

“In a business where there are a lot of reprehensible people, he stood out as particularly dishonest, obnoxious, self-centered,” is how one former colleague described working with O’Reilly.

He was a “pompous jerk,” added Rory O’Connor, who went to high school with O’Reilly and then worked with him at Channel 5 in Boston. O'Connor told Boston magazine that O'Reilly “was despised in the newsroom --  but he didn't care.”

Marvin Kitman, who interviewed O'Reilly more than two dozen times for the biography he wrote about the broadcaster, told Media Matters in a 2015 interview, “He’s a pretty lousy human being.”

But don’t take their word for it. Take it from the man who gave O’Reilly his Fox News perch, Roger Ailes:

I said Bill, you’re authentic. You’re an authentic prick. It’s just not on the air. Like, you’re a prick to your staff, you’re a prick to management. You’re a prick to your family. You’re authentic. You’re actually a prick. And that has allowed you to become very successful.

But it allowed him to become successful only because Fox News embraced O’Reilly’s persona and built a cable channel around it. And then it spent years looking the other way and enabling its top-rated host despite numerous incidents of reported harassment -- because he made the network money.

Today, Fox is belatedly trying to clean house. But the culture runs deep.