Facebook CEO Mark Zuckerberg will testify before Congress tomorrow. It turns out Cambridge Analytica scraped way more user data than everyone initially realized, and other third parties have probably purloined data on most of the platform's two billion users. Congress, like most everyone else, wants answers.

But Zuckerberg also has a big problem: Selling user data is its business model. It provides its platform to users for free so it has to make money somehow.

This really goes back to the birth of Facebook, Google, and much of the rest of Silicon Valley. "There was this very kind of pure-hearted activism — coming from the left, actually, at the dawn of the internet age — saying, 'Everything should be free'," explained Jaron Lanier, a virtual reality pioneer and one of the tech industry's godfathers. "'We should have free email, free social networking, free news, free, free, free.'"

You can see this idealism in a lot of Zuckerberg's activist pushes for building out free internet access to people around the world, particularly in the most impoverished countries. It's also built into the architecture of Facebook itself. "We were very focused on social experiences and pretty idealistic: We believed in a world where people could share and experience things together," Sheryl Sandberg, Facebook's second-in-command, told NBC. "And we just weren't thinking enough about the bad use cases."

As long as you can get to the internet, you can sign up for a Facebook account. And bingo: You're connected to friends, family, colleagues, the world.

Yet nothing is really free. Facebook may be composed of digital signals, but it's still produced by the labor of programmers, technicians, and lots of other people. They need to be compensated for their work. Entrepreneurs aren't just going to eat those costs themselves.

The only way to resolve the conundrum is to rely on ad revenue.

Certainly, the company wants to keep its users happy as well — not least because nervous users make for nervous advertisers. Facebook already has some limited barriers to prevent data from going to third parties. And it just announced that the stringent privacy standards it must adhere to in the European Union will be applied to the entire site across the globe.

But fundamentally, there's no option for Facebook users to totally, 100-percent opt out of their profile data being used for targeted ads. There can't be. Relying on revenue from advertisers inevitably means that, in some way, Facebook must make use of members' data — and allow third parties to make use of it — to remain financially viable. There's a reason it took this massive scandal to get Facebook to apply EU-style standards globally. And there's a reason Facebook may not have looked too closely when third parties like Cambridge Analytica were up to their shenanigans. As much as Facebook wants to keep its users happy, the data must flow.

"Our service depends on your data," Sandberg admitted in that same interview. If total opt-out was an option, Facebook "would be a paid product."

And if we did pay to use Facebook, then who does and doesn't get to access its connectivity would become a question of affordability. The middle- and upper-classes would be able to pay, but the poor and the working class might not. The people of the developed nations would enjoy access, but not the people of still-developing nations. The vision of a free internet would be dead. You can almost hear Sandberg begging the viewers not to kill the dream.

Except there are other ways to achieve the goal of free and universally accessible internet services. In an ideal world, everyone would be rich enough to be able to afford a paid Facebook. In a less perfect world, the government could also simply provide internet access and services like Facebook itself.

But even then, we'd still be thrown back on the problem that nothing is free. In that case, the question would be, who do we tax to finance this policy? The obvious progressive answer: tax wealthy people like Sandberg and Zuckerberg.

And that's the thing. As Lanier pointed out, we didn't just want a free internet: "At the same time, we love entrepreneurs. We love tech companies. We love Steve Jobs, we love Bill Gates, so we have to combine these two things." Facebook and much of the rest of Silicon Valley was supposed to be high-minded; not just another grubby capitalist consumer product. But as long as it's a private business, it can't escape its profit motive.

Facebook's owners benefit from this ideological shell game: The company has become one of the internet's monopolist choke points. Huge portions of all the advertising revenue that flows to media content producers must go through the platform. That's allowed Facebook to extract vast amounts of wealth, leaving all sorts of other businesses scrambling for financial survival.

That, as much as anything else, is probably why Sandberg and Zuckerberg don't want the dream of a "free" internet to die.