It depends on who buys the data and / or the interpretation of that data from them. Just imagine a country like China buying it to predict who will become a subversive and arresting them before anything happens, something akin to pre-cog crime. When I think about it, we can probably aleady do this somewhat accurately with all the data we can collect right now. We have all the tools: open (and affordable proprietary) ML software, open big data frameworks (hadoop, storm, actor model, cassandra), as well as the cloud (AWS, Rackspace). People just need a comprehensive set of data.
> Smarter people mean less susceptibility to manipulation, which is what we are really trying to achieve, right?
Not necessarily, you can't constantly consciously fight thousands of years of evolution; but that's another topic.
Then there's the argument that in 30 years the US will be one of these countries, too. I wonder why people are so afraid of this, but not of the small chance that they'll be hit by a meteor when they go outside tomorrow to go to work. They've been hit by a meteor exactly as many times as their government has used a "social graph" to oppress them, after all.
You're vastly underestimating the potential value of access and storage of more and more precise behavioral data combined with the innovation of a startup vs the stodgy, uncreative, stubborn ways of both old world telecom and finance corporations. Back then, even with access to people's purchasing data and past addresses, I would have had to do a lot more work and ask for larger increases to our budget to figure out people's relationships as well as non-purchasing behavioral data aside from traffic. Now I can potentially have access to people's preferences to stuff as opposed to just guessing. Today it's much easier and cheaper.