These tech execs have regrets about the world-changing sites they helped create

In November, Sean Parker, who cofounded Napster before becoming Facebook's president, told Axios that the social network has had unintended consequences on how society functions.

"I don't know if I really understood the consequences of what I was saying, because [of] the unintended consequences of a network when it grows to a billion or 2 billion people and ... It literally changes your relationship with society, with each other ... It probably interferes with productivity in weird ways," Parker said. "God only knows what it's doing to our children's brains."

Snap CEO Evan Spiegel recently admitted that he believes social media has fueled the rise of fake news.

"The personalized newsfeed revolutionized the way people share and consume content. But let's be honest: this came at a huge cost to facts, our minds and the entire media industry," he wrote in an op-ed for Axios.

"Social media fueled 'fake news' because content designed to be shared by friends is not necessarily content designed to deliver accurate information," Spiegel continued. "After all, how many times have you shared something you've never bothered to read?"

A former product manager at Facebook, Antonio Garcia Martinez, has said Facebook has not been forthcoming about its ability to influence users based on the data it collects on them.

"Facebook deploys a political advertising sales team, specialized by political party, and charged with convincing deep-pocketed politicians that they do have the kind of influence needed to alter the outcome of elections," he wrote in an op-ed for The Guardian earlier this year.

In 2016, Martinez published a book, "Chaos Monkeys," about his work there.

Chamath Palihapitiya, who joined Facebook in 2007 and became its vice president for user growth, recently said the "dopamine-driven" social network is destroying how civil 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," he said at a conference at Stanford Graduate School of Business.

He gave the example of an incident in India where fake messages about kidnappings shared on WhatsApp contributed to the lynching of seven innocent people.

"That's what we're dealing with," he said. "And imagine taking that to the extreme, where bad actors can now manipulate large swathes of people to do anything you want."

For that reason, Palihapitiya recommended people take a "hard break" from social media. He later added that he believes Facebook also "overwhelmingly does good for the world."

Last week, Facebook's director of research, David Ginsberg, and research scientist Moira Burke published a post that details the effect that Facebook may have on our moods.

They pointed to a study from University of Michigan, which found that students who read Facebook for 10 minutes were in a worse mood at the end of the day than students who posted or talked to friends on Facebook. And in a survey by UC San Diego and Yale, researchers found that people who clicked on about four times as many links as the average person, or who liked twice as many posts, reported worse mental health than average.

"In general, when people spend a lot of time passively consuming information — reading but not interacting with people — they report feeling worse afterward," Ginsberg and Burke wrote. "We don’t have all the answers, but given the prominent role social media now plays in many people’s lives, we want to help elevate the conversation."

They added that the company is looking into these issues to improve its products.