The farm is at risk at all time.
That said, I think the risks are way smaller than previous era's trustbusting. I like FB as an example, as I said. I'm pretty confident that FB would be pretty much the same on far less revenue because they were pretty much the same on less revenue in recent years.
Comparable social media services run of far less revenue (scaled whichever way you like). You can also look at their accounts, which reveal a lot. The simplest clue is profit margins.
If we're wrong... one social media service declines and another takes its place. Personally, I see very little risk. The actual risk, IMO, is not really about keeping these services viable. There no "shit! I broke auto-manufacturing and now we don't have cars" risk.
It's about share price. Smallish declines in revenue can mean big declines in profit. Any decline in revenue can lead to a collapse of share prices, regardless of profit. The big techs are a big part of the S&P, and high profile. Quite a lot of the S&P's value relates directly to monopoly, so antitrust (IMO) directly conflicts with equity values... and things could get "macroeconomic" from there.
All that said, I'm not advocating anything intentionally destructive. Google is, I suspect, expecting to be broken up eventually. I think that was part of the Alphabet restructuring logic.
The primary objection that comes to my mind, in the vein of your comment,is a hayek-esque information argument. A Hayekian logic though, is totally incompatible with paragraph 5 above though, and I'm quite confident about that... so I don't know where it fits in.