Facebook’s founders knew they were creating something addictive that exploited “a vulnerability in human psychology” from the outset, according to the company’s founding president Sean Parker.

Parker, whose stake in Facebook made him a billionaire, criticized the social networking giant at an Axios event in Philadelphia this week. Now the founder and chair of the Parker Institute for Cancer Immunotherapy, Parker was there to speak about advances in cancer therapies. However, he took the time to provide some insight into the early thinking at Facebook at a time when social media companies face intense scrutiny from lawmakers over their power and influence.

Parker described how in the early days of Facebook people would tell him they weren’t on social media because they valued their real-life interactions.

“And I would say, ‘OK. You know, you will be,’” he said.

“I don’t know if I really understood the consequences of what I was saying,” he added, pointing to “unintended consequences” that arise when a network grows to have more than 2 billion users.

“It literally changes your relationship with society, with each other. It probably interferes with productivity in weird ways. God only knows what it’s doing to our children’s brains,” he said.

He explained that when Facebook was being developed the objective was: “How do we consume as much of your time and conscious attention as possible?” It was this mindset that led to the creation of features such as the “like” button that would give users “a little dopamine hit” to encourage them to upload more content.

“It’s a social-validation feedback loop … exactly the kind of thing that a hacker like myself would come up with, because you’re exploiting a vulnerability in human psychology.”

Parker, who previously founded the file-sharing site Napster, joined the Facebook team in 2004 five months after the site had launched as a student directory at Harvard. Parker saw the site’s potential and was, according to Zuckerberg, “pivotal in helping Facebook transform from a college project into a real company”.

In 2005, police found cocaine in a vacation home Parker was renting and he was arrested on suspicion of possession of a schedule 1 substance. He wasn’t charged, but the arrest rattled investors and he resigned shortly after.

Thanks mostly to his brief stint at Facebook, Parker’s net worth is estimated to be more than $2.6bn. He set up the Parker Foundation in June 2015 to use some of his wealth to support “large-scale systemic change” in life sciences, global public health and civic engagement.

Parker is not the only Silicon Valley entrepreneur to express regret over the technologies he helped to develop. The former Googler Tristan Harris is one of several techies interviewed by the Guardian in October to criticize the industry.

“All of us are jacked into this system,” he said. “All of our minds can be hijacked. Our choices are not as free as we think they are.”