A new Gallup poll, which was conducted in the lead-up to Zuckerberg's trip to Capitol Hill and released Wednesday, found that 43 percent of users are "very concerned"-a 13-point jump from the last survey in 2011-and 31 percent are "somewhat concerned" about privacy on the platform".
The Facebook CEO's at-times awkwardness saw him being compared to Star Trek's Data - an android who struggles with human behaviour and emotions.
Some analysts said Zuckerberg's appearance suggests a new path forward for social media under closer scrutiny. Zuckerberg will testify for the second day in a row when he stands before the House Energy and Commerce Committee on Wednesday to answer additional questions.
"The Internet is growing in importance around the world in people's lives, and I think that it is inevitable that there will need to be some regulation", he told lawmakers.
"We are two women of color, how are we unsafe?"
Democratic Representative Debbie Dingell expressed frustration with Zuckerberg's frequent promises to get back to lawmakers later in writing.
Zuckerberg's reply: "It will not be shared with third parties". For the past 14 years Facebook has been much more interested in exploiting the personal data rather than protecting personal data. Cambridge Analytica's activities affected roughly 5.6 lakh users in India, after around 335 people in India downloaded an app called mydigitallife, and 87 million users worldwide, according to the tech giant. He gave no further details.
He said Facebook is contemplating legal action, saying there might be a slew of apps that collected data on Facebook users in a similar fashion to Cambridge Analytica.
Some of the lawmakers talked to Zuckerberg, 33, as they would their children or grandchildren, and were occasionally befuddled by the complexities of his company. It will look for misuses of personal information and then alert users if it finds anything suspicious.
Zuckerberg was unable to answer Dingell when she asked how many website pages had such buttons.
Responding to a question, Zuckerberg acknowledged that a lot of people probably just accept terms of service without taking the time to read through it.
"I started Facebook, I run it, and I'm responsible for what happens here", he continued.
How much data does Facebook collect on users - and non-users? He refrained from cracking jokes and flashed few smiles. Over the two days, the value of Zuckerberg's stake in the company grew about $3 billion. He did not name specific companies.
Rep. Jan Schakowsky, a Democrat from IL, recounted a long list of Zuckerberg's apologies over the years before concluding: "This is proof to me that self-regulation does not work".
"The only way we're going to close this trust gap is through legislation that creates and empowers a sufficiently resourced expert oversight agency, with rulemaking authority to protect the digital privacy and ensure that companies protect our users' data".