James Martin/CNET

Imagine you stopped using everything owned by Facebook, Google and Amazon right now. How difficult would your life be?

Despite all the privacy concerns surrounding tech giants, billions of people are still using their services. It's because there's nowhere else to go, experts said.

On Tuesday, academics and industry experts told the Senate Judiciary Committee that the issue with privacy and tech giants is that there's no competition. Tech giants have gotten immensely powerful, they noted, pointing out that if one company had a major data privacy problem, there would be no alternative to turn to.

"That's what brings us here today, the lack of choice," said Sen. Richard Blumenthal, a Democrat from Connecticut. "The excessive and extraordinary power of Google and Facebook and others who dominate the market is a fact of life."

Facebook and Google didn't respond to a request for comment.

As scandals erupted over the last year, some movements launched to get people to leave this or that tech platforms, but they barely made a dent. After Facebook's Cambridge Analytica scandal last March, for instance, a call to delete Facebook rang throughout social media. But when the dust settled, Facebook lost fewer than 15 million users -- a drop in the bucket as more than 2 billion people continue to use the social network every month.

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"People need to be able to decide how their data is used by these companies," Johnny Ryan, chief policy and industry relations officer of Brave, which makes a privacy-focused browser, told lawmakers. "When the scandal happened with Cambridge Analytica, people only had this one choice -- delete Facebook."

He argued that if there were more competition in social networks, people would have had more options in the backlash against Facebook. The push to delete Facebook failed to catch on because the tech giant dominates so much of social media, while also owning its closest competition, Instagram.

"My concern is that if I look at my daughter, and you say to her, all your friends are on Facebook, and this user agreement means you give up your privacy, she's going to click yes because she wants to talk to her friends," said Brian O'Kelley, founder and former CEO of ad tech giant AppNexus.

This lack of competition is the root of privacy issues for tech companies, experts said, and why several lawmakers have called for a breakup of Facebook. The same could be coming for Google.

"There are many on this committee, including myself, concerned about anti-competitive conduct from Google," Sen. Ted Cruz, a Republican from Texas, said at the hearing.

Google has the lion's share of users, with the world's most popular mobile operating system in Android, the most popular browser in Chrome and billions of people on YouTube, plus Gmail, Maps, Chromebooks and its search engine.

There are alternatives that are privacy-focused, such as DuckDuckGo for search, ProtonMail for email and Brave for browsers, but their total users are only a fraction of Facebook's and Google's users.

At the International Association of Privacy Professionals Summit in early May, the founders of those three companies all noted that they were seeing growth, but it's not at the same pace that tech giants have.

"It's a question we get asked a lot, are we going to be a Google killer? No. But do 5, 10, even higher percent of people want a private alternative for major services? Yes, and that's a large business," Gabriel Weinberg, founder of DuckDuckGo, said at the conference. He noted that DuckDuckGo accounts for about 1% of searches in the US.

But even if tech giants with privacy issues were broken up, it would take decades to see real change, Fiona Scott Morton, an economics professor at Yale University, told lawmakers.

Unlike with competition in other markets -- like going to Burger King if you don't like McDonald's -- tech companies dominate the market and easily squeeze out alternatives, Morton explained.

"If there were more choices in the marketplace, we wouldn't be worried about these problems," she said.