What the government wants to accomplish with the Facebook hearings, political grandstanding and blathering, is a harness, control to their political power benefit. They're playing a political game of conquest. There is no scenario where they're going to destroy it.
As a rule, DC doesn't like power competition, and they absolutely do not tolerate it from the private sector. One of the dumbest things Bill Gates ever did was crack a joke that he was as powerful as the President [1]. They're fine with people being enormously rich or famous, and having some modest influence derived from that, it has to be under their feet however, it has to squarely fall beneath their political power. There's nothing the savages in DC dislike more than private power that doesn't pledge fealty. They will break Zuckerberg and force him to retire from Facebook if he doesn't capitulate. One way or another they will get what they want. Zuckerberg's only choice is whether he gives it to them willingly, or they take it from him. He is delusional if he believes his voting interest in Facebook leaves him primarily in control of Facebook's destiny at this point, such that he can stand against Congress.
Zuckerberg is fighting them so adamantly, for now, because he still views Facebook as his. That's part of his latest response, in which he has clearly shifted positioning, and now proclaims FB will stop apologizing. The DC power is particularly agitated by that, they view it as a more direct challenge to their authority. And it's that point on which he is mistaken, Facebook no longer belongs to him in regards to control. What's going on now is the action required to formally begin removing his sole control over Facebook. The political power views people like Zuckerberg as being allowed to exist, allowed to operate, in a permission sense. It's important to understand how the bureaucrats in DC view the world. Gates for a long time thought he could hide up in the Pacific Northwest, stay out of DC politics, and just keep playing in his software kingdom (eventually the tech industry and Microsoft got too big for that). The Google founders, along with Schmidt, realized a lot earlier on that they had to be deep into DC lobbying to try to preempt, shape, the inevitable political harness. During the anti-trust questioning, Gates got emotional about what he perceived to be the government trying to kill Microsoft [2]; what that response really was, is Gates feeling like control over his kingdom was being taken from him; and that's exactly the spot Zuckerberg is in now.
[1] "Bill said, 'Of course, I have as much power as the president has.' Melinda's eyes got wide, and she kicked him under the table, so then he tried to play it off as a joke. But it was too late." https://www.wired.com/2000/11/microsoft-7/
[2] "What startled [DOJ anti-trust chief] Klein was the personal terms in which Gates made these points. "It wasn't just, You're going to kill my business; it was, You're going to kill me. And clearly we, the government, were the instrument of this great personal affliction."