Looking at the 2008 crisis debacle and “too big too fail”, maybe it wouldn’t be that bad. If your company has an impact on the level of a public utility, maybe it should be regulated like one.
And God knows that Zuckerberg’s lifestyle wouldn’t change much if he was only a “simple” billionaire instead of a multi-billionaire ;)
I imagine regulation is coming. If not specifically for Facebook, then changes in privacy law in the US to edge closer to what the EU enjoys are forthcoming as soon as the US elects a Democratic House.
The US is a capitalist country. It will see how much negative impact the GDPR has on businesses and consumer choice, as websites block EU traffic in droves, and will not make that same mistake.
Let’s not even go down this road, it has been the source of very long discussions. I’ll just say that nobody in the US wants the liability of EU traffic under GDPR except for very large companies with expensive legal teams.
That follows from "successful enough" meaning impacting a large fraction of society in some way - which is the government's area of competence. So they definitely will be interested in your impact, and whether or not your market-driven priorities are at odds with well-being of society.