SAN FRANCISCO • Mr Mark Zuckerberg rose to wealth and fame with a mission of connecting people, but he now faces the wrath of users outraged that he is not doing more to defend their data.

The latest crisis laying siege to leading online social network Facebook has raised the spectre that he has lost control of his creation and been naive about the unintended consequences of people sharing so much about themselves.

"If Facebook was a typical company, and Zuckerberg was the founder, he would probably be gone," said tech industry analyst Rob Enderle of Enderle Group.

"He looks like a guy who really doesn't know what he is doing. He is not the hero that a lot of people had viewed him as; his reputation and image are badly damaged."

Facebook has prospered on digital advertising that benefits from being able to use what people share about themselves to target ads. But if it was betting on people's better natures when it came to truthful sharing and respecting others, it was not always a winning wager.

The California-based social network has been a flashpoint for controversies about bullying, harassment, free speech, extremist propaganda, election meddling, privacy, and more.

"They don't put enough effort into making sure the user is protected and the experience is assured," analyst Enderle said. "They only care about the advertisers, and the user is basically a digital slave."

A public apology by Mr Zuckerberg has failed to quell outrage over the hijacking of personal data from millions, as critics demanded the social media giant go much further to protect user privacy.

Belatedly speaking out about the harvesting of Facebook user data by a British firm linked to Mr Donald Trump's 2016 election campaign, Mr Zuckerberg admitted on Wednesday to betraying the trust of its more than two billion users, and promised to "step up."

He wrote a 935-word Facebook post in which he said "we have a responsibility to protect your data, and if we can't then we don't deserve to serve you", and outlined steps the firm was taking following reports about user data being scraped without consent.

He sat for interviews with the New York Times, Wired, tech publication Recode and a rare on-camera interview with CNN. But despite the post and parade of media interviews, crisis experts argue that the 33-year-old billionaire's personal response came much too late.

Though the firm had issued statements and other executives had made remarks on social media, Mr Zuckerberg did not speak up until five days after the crisis erupted - a veritable lifetime in today's crisis playbook. "I believe you have about 15 minutes to get on top of these things," said Ms Davia Temin, a communications and management coach on reputation issues.

Facebook, she said, "defines real time for our world, so the expectation for them is that they would be real time too."

The great irony of such a delayed response is that it came, of all places, from the CEO of Facebook. It was Mr Zuckerberg, after all, who founded the platform that is perhaps most responsible - in addition to Twitter - for the expectation that leaders speak up immediately.

It has also contributed substantially to a society that expects immediate gratification, one where users post photos of their baby's first steps or the artisanal meal they just ate and wait eagerly for their friends' "likes" and comments.

"For the company that did so much to create the instant reaction society, to not have a response in real time from its CEO is surprising," said Ms Carreen Winters, chief strategy officer for MWW Public Relations.

More than US$50 billion (S$66 billion) has been wiped off the market value of Facebook, whose US$16 billion IPO in 2012 was structured to keep control of Facebook in the hands of Mr Zuckerberg.

He has said he is happy to testify before the US Congress. The leaders of the US House Energy and Commerce Committee last night formally asked him to testify at a future hearing.

AGENCE FRANCE-PRESSE, WASHINGTON POST