UNFRIENDED: Here are all the Mark Zuckerberg allies who have turned on Facebook

Roger McNamee mentored Mark Zuckerberg and then wrote a book about how terrible Facebook is.

McNamee was an early investor in Facebook, and once a mentor to Mark Zuckerberg when he was a young founder. But in January 2018 — before the Cambridge Analytica data scandal broke — McNamee went on the warpath, accusing his former protégé and Facebook of becoming "toxic" in newspaper op-eds. He went on to expand on his ideas in a book titled "Zucked: Waking Up to the Facebook Catastrophe."

Justin Rosenstein, the former Facebook engineer who invented the 'like' button, refuses to use social media.

Justin Rosenstein was an early employee at Facebook, and quit in 2008. He's now cofounded a startup called Asana with Dustin Moskowitz, one of Facebook's founders.

In a 2017 interview with The Guardian, Rosenstein said he's sworn off all social media and described "likes" on Facebook as "bright dings of pseudo-pleasure."

Facebook cofounder Chris Hughes, who thinks the company should be broken up.

Chris Hughes is a cofounder of Facebook, and left the company relatively early on to volunteer for Barack Obama's presidential campaign.

In an astonishing opinion piece for The New York Times, Hughes called for the breakup of Facebook, saying that the social network, WhatsApp, and Instagram should be three separate public companies.

"Mark is a good, kind person," he wrote of Zuckerberg. "But I'm angry that his focus on growth led him to sacrifice security and civility for clicks."

Brian Acton, the cofounder of WhatsApp who told people to "delete Facebook."

One of Facebook's smartest decisions was to acquire WhatsApp for $19 billion in 2014.

But WhatsApp's founders, Brian Acton and Jan Koum, are privacy-obsessed characters, who inevitably clashed with an acquirer whose entire business was making money via the mass collection of people's information. Acton left Facebook in 2017 and promptly began advising a WhatsApp competitor, messaging app Signal, and told people to "delete Facebook."

In an explosive interview with Forbes, he also detailed icy exchanges with Zuckerberg. According to Acton, Zuckerberg told him in one of their final meetings, "This is probably the last time you'll ever talk to me."

Jan Koum, the other WhatsApp cofounder who flounced out after clashes with Facebook's executives.

Jan Koum confirmed in April 2018 that he planned to leave Facebook, quitting only a few months after his cofounder.

Although Koum has been more circumspect in his remarks about Facebook, The Washington Post reported that he had clashed directly with Facebook over its plans to monetise WhatsApp. Like Acton, Koum was made a billionaire when Facebook acquired his company for $19 billion.

Facebook's founding president, Sean Parker, who warned about social media's impact on people's mental health.

"God only knows what it's doing to our children's brains," Sean Parker told Axios in November 2017, in reference to social media.

Parker, the first president of Facebook and one of its earliest investors, said bluntly in the same interview that the company had been designed to exploit "vulnerability" through features such as 'likes.'

It was an astonishing admission from someone so closely associated with Facebook's early success.

Leah Pearlman, the co-inventor of the 'like' button who is haunted by "Black Mirror."

Pearlman is a former manager at Facebook, and now an illustrator. She developed the concept for what became the "like" button on Facebook, eventually working with then coworker Justin Rosenstein, and other employees to bring it to life.

Although the idea was intended to bring more positivity to the social network, Pearlman has come to worry about the dynamics of the like button and the wider idea of engagement.

In a 2017 interview with The Ringer, Pearlman said she was haunted by a "Black Mirror" episode where people's social credibility hinges on a peer-to-peer ratings system. "I just watched that about a month ago, and that haunts me on a pretty regular basis," she said at the time. "Because it's not that far off."

Chamath Palihapitiya, a former Facebook executive, said Facebook was destroying how society works.

Like Sean Parker, ex-Facebook executive Chamath Palihapitiya worried about the effect of constant dopamine hits provided by the social network.

In a November 2018 interview at Stanford, Palihapitiya said: "The short-term, dopamine-driven feedback loops that we have created are destroying how society works. No civil discourse. No cooperation. Misinformation. Mistruth. And it's not an American problem. This is not about Russian ads. This is a global problem. So we are in a really bad state of affairs right now, in my opinion."

Palihapitiya later walked back his remarks but, Wired reported in 2019, the comments particularly hurt insiders. The magazine reported that COO Sheryl Sandberg sometimes wears a necklace welded together from one given to her by Mark Zuckerberg, and another given to her by Palihapitiya.

Sandy Parakilas, the former Facebook operations manager who played a major role in educating the public about Cambridge Analytica.

Sandy Parakilas, as he tells it, was comparatively low down in the pecking order when he worked at Facebook between 2011 and 2012.

But he was involved in an element of Facebook's platform that would become crucial to the Cambridge Analytica data scandal in 2018. And amidst all the confusion about what had actually happened, Parakilas could give a clear explanation of how Facebook hadn't policed the third-party developers plugging into its platform.

Parakilas spent much of 2018 jetting around the world testifying to various governments about the disaster, and holding Facebook to account. "I'm pretty sure Mark Zuckerberg and Sheryl Sandberg do not appreciate what I'm doing," he told Business Insider last year. "I have no intention of stopping until the company is doing all it needs to do to protect our elections."

Instagram cofounder Kevin Systrom, who resigned abruptly from Facebook six years after acquisition.

Facebook's other extremely smart acquisition was Instagram, which it bought for a comparatively modest $1 billion.

Systrom and his cofounder Mike Krieger stuck around at Facebook for six years after the acquisition, but the pair abruptly resigned in September 2018 for reasons that still aren't entirely clear.

Six years is longer than usual for an acquired founder to hang around but Systrom hinted in onstage interviews that things hadn't necessarily ended well. "No one ever leaves a job because everything's awesome, right? Work's hard," he said in 2018.

Honorable mention: Chris Cox, a beloved Facebook employee who isn't sure about Mark Zuckerberg's new vision.

Chris Cox was, until recently, chief product officer at Facebook and one of its most beloved employees.

Cox has not been openly critical of Facebook, but has suggested that he disagrees with the company's new direction, where it will knit the backends of Facebook, WhatsApp, and Instagram together.

He told Yahoo Finance in an interview that he left Facebook over "artistic differences."

Honorable mention: Former Facebook product manager Antonio Garcia Martinez

Martinez, a journalist and former Facebook product manager, is not as outspoken in his criticism of the social network as others on this list. And he is often critical of the way journalists cover the company.

But he has admonished Facebook for allowing the Cambridge Analytica data scandal to happen, and Mark Zuckerberg for behaving in a robotic fashion. He has also accused the company of "lying through their teeth" about the way its ad platform works.

Honorable mention: former chief privacy officer, Alex Stamos

Alex Stamos was Facebook's chief security officer at a crucial time in its history: just as its platform was being abused by Russian trolls and agents to influence the US presidential election. Stamos tried to warn Facebook's leaders and board of the threat but, as he told it to Yahoo Finance, his style and approach resulted in his being pushed out.

He has taken a nuanced approach to commenting on Facebook, and arguably defended the firm more than he's criticised it. But he has hinted that it had been tough to work at the company. "Obviously, it has been a difficult three years," he told the New York Times. "I'd like to take the things I've learned and apply them more broadly."

Honorable mention: Facebook cofounder Eduardo Saverin, who had a bitter legal dispute with Facebook.

Saverin is, interestingly, not a current critic of Facebook, telling Forbes in a recent interview that he was "proud" of Mark Zuckerberg and COO Sheryl Sandberg.

He remains a shareholder in Facebook but, in its early days, was embroiled in multiple lawsuits with the company over his stake in the company. All were settled out of court, and Saverin signed an NDA.