Buck made the comparison in a tweet on Saturday writing, "Big Tech is the new Big Tobacco. They are harming our kids for profit."
Speaking on "Fox News Live" on Sunday, Buck explained the comparison, arguing that young people were lured in without "appropriate warnings" and that the tech giant ignored data.
A Facebook spokesperson did not immediately respond to FOX Business’ request for comment on Sunday.
Facebook has received bipartisan criticism from lawmakers following the report.
Sens. Richard Blumenthal, D-Conn., and Marsha Blackburn, R-Tenn., — chair and ranking member of a Senate commerce subcommittee on consumer protection — on Tuesday announced plans to investigate the tech giant over its knowledge of Instagram's impact on teens, and specifically, teenaged girls.
Both Blackburn and Blumenthal said that Facebook has known about Instagram's impact on minors and the Democratic senator wrote in a statement posted to his Twitter account on Tuesday that "its own employees’ warnings were shoved aside in favor of growth-at-all-costs."
Researchers tapped by the tech giant to examine the app's impact on young users' mental health over the past three years found that 32% of teen girls who "felt bad about their bodies" said Instagram made the issue worse, according to company documents obtained by The Wall Street Journal.
One 2019 slide on the Instagram researchers' presentation to Facebook reviewed by the Journal said the app makes "body image issues worse for one in three teen girls."
"Teens blame Instagram for increases in the rate of anxiety and depression," another slide read, according to the newspaper. "This reaction was unprompted and consistent across all groups."
Some users also attributed time spent on the app to experiencing suicidal thoughts; 6% of American users indicated a connection between the two compared to 13% of UK users, the slide presentation reviewed by the WSJ said.
Karina Newton, Instagram's head of public policy, said in a Tuesday blog post that it stands by its research on Instagram, which demonstrates the company's "commitment to understanding complex and difficult issues young people may struggle with, and informs all the work" Instagram does "to help those experiencing these issues."
On Wednesday, Democratic lawmakers Sen. Ed Markey of Massachusetts, Rep. Kathy Castor of Florida and Rep. Lori Trahan of Massachusetts sent a letter to Facebook CEO Mark Zuckerberg asking if he has personally reviewed Instagram's findings regarding the app's impact on teen girls and if Facebook could provide an update on its efforts to make the platform safer for minors who may be struggling.
Buck pointed to the Facebook data saying on Sunday that "their own data shows that teenage girls have depression issues, they have issues about their own bodies, they are really more self-dangerous."
"And so the problem that Facebook has is how to get out of this situation," he continued, arguing that the company is a "monopoly."
"They act like a monopoly and they don’t react to the dangers that they’re causing," Buck continued.
He added that he believes that the courts should examine whether Facebook and Instagram "should still be merged or whether they should be separated."
More than 40% of Instagram’s users are under 22 years old, and about 22 million teens use the app every day, WSJ reported, citing Facebook's documents.
Buck said that he believes "what we have to do in Congress is to make sure that we give teenage girls, teenagers and particularly parents the ability to find safer competitors to Facebook and Instagram so that those young people aren’t placed at risk in the way that they are right now."
FOX Business’ Audrey Conklin contributed to this report.