Railways and telecoms worked out just fine.
Sure, in many countries, train tickets have been getting overly expensive under government control but high costs are not such a huge concern in the grand scheme of things. On the other hand, the break up of AT&T in the US had huge benefits for consumers in terms of lowering costs.
If Facebook is nationalized, at least they will not manipulate people to serve corporate interests (that is the main threat).
Sure, in the worst case, under government ownership, social media might be used to manipulate elections to give preference to the incumbent party over the other, but that is infinitely better than manipulating elections based on the financial interests of a tiny minority and allow it to drive an increase in surveillance and restrictions of public freedoms. Eventually, even the tiny minority of shareholders (the smaller ones) will end up being harmed at the expense of the bigger shareholders. It's not going to stop at non-shareholders.