What has Facebook done? Copied all of Snapchat and displayed some russian ads.
I'm not really sure what to tell you - something closely approximating omniscience will be in the hands of a few organizations ran by a few people in 20 years. Hopefully society wisens up. This will be an interesting century. I would personally pick Monsanto if I were you.
Everybody has their version of the apocalypse.
No one cares which companies are the worst, they are all bad in their own way, but if you claim that the number one priority is to break up Facebook because they could harm people in the future with their omniscience, then don't get mad when someone calls you out and tells you it's been happening for decades, even without all of that techno-knowledge you are so afraid of.
But they know where you are and what you do! yes, so what, they can harm you without knowing, they have been. They've been telling people what to think since they invented talking.
Superintelligence is coming and guess what? Governments are gonna own it, full stop. Not a company, not two. Governments, with guns. And for the looks of it is gonna be China. The NSA has been fighting against the odds this whole time but who knows, maybe they still have a chance. Facebook is just a pawn, the tip of the wedge, and you've fallen for the distraction.
Or do you really think breaking up facebook will completely halt development of AI?
1) How vast the useful data gulf is between Google/FB and dozens of other entities. Maybe they have more data overall and had a decade head start, but at this point there's tons of other software, hardware and data stakeholders that can construct a pretty complete map of your life. And even before Google/FB there was the whole financials infrastructure: banks, credit agencies, etc.
2) How actionable that data advantage is for Google/FB. Let's say you're right and they know a lot more than the next most knowledgeable entities. They're still constrained in how they can actually use that to manipulate your life to whatever nefarious ends. They're already under a lot of scrutiny, which is good, and no doubt will remain so. There are many obvious and overt steps they'd have to achieve (all of which would garner huge backlash) before consolidating some kind of truly hegemonic power. The leap from "has the best information" to your sci-fi scenarios is pretty significant for non-government entities with like-sized competitors to worry about in the private sector.
I'm not for breaking them apart but I am for limiting their data collection and privacy invasion outside of their own products.