The goveernment can use the data to ruin your entire life. Either by shooting you with the guns they have, and get to use fairly easily. Or using their "justice" system to incarcerate you in a cage for an extended period of time. All google and facebook will do with your data is try to sell it and make some cash. They don't want you in a cage, or dead, because they make money off your search terms and profile.
And since most americans commit 3 felonies a day without knowing it (because their are soooooo many laws), it wouldn't be hard to end up in prison if you piss off the wrong bureaucrat.
A perfect example of this is the kid in texas that has been in jail since april for a distasteful joke on facebook. Facebook might have simply suspended his account, or banned him. But they surely won't show up with guns and put you in a cage.