I can see where you're coming from.
1. I feel sorry, on some level, for the people who are not aware of the personal data that they are leaving open, because they are ignoring a valuable asset that they have in that data. At the same time, however, they are taking advantage of that asset, whether they realize it or not.
2. Personally, I am aware of the asset that my data is, and I'm aware of how I'm sharing that asset. I'm aware of how these corporations are utilizing my "very, very personal details" and I've come to terms with it.
3. Personally, I'm actually really open with Facebook and Google, primarily (slashdot is in this on some level as well, but I don't post on slashdot near as much as I do elsewhere, just because I'm more of a lurker than a poster here, the majority of the time--sometimes, that does change and I get in a posting mood, like this; I do make a point to post on slashdot occasionally, because I see that as me giving them my data in exchange for them providing me the tool that slashdot is for me). I do so realizing what I'm doing, however. I realize that when I get into a debate on Facebook that reveals particularly personal information about me, or when I search Google for particularly personal details, or when I visit a website that reveals particularly personal details about me, that I am sharing this data about me. However, I see that as my payment for the service that is provided for me.
For instance, I'm active in poetry/spoken word. Typically, I pay $5 for 2 hours of a forum to share/hear poetry/spoken word. Rather than paying $5 for 2 hours on the forums that the internet provides me (namely Facebook and Google, again), I'm providing them data about me. These companies turn around and make that data into money. I'm fully aware of this happening, and have accepted it as me utilizing the asset that is my personal data in the form of indirect money from a third party source.
This does not create an issue for me, because I'm aware of it, I accept it, and I make the educated decision to trade my data for a service. It sounds like you would rather not provide that data for that service. I can understand that. However, I value the service, and I see it is an acceptable trade. They make their money off of my data, and I get the service that I desire in exchange.
I think it comes down to different mindsets about the matter. I see my personal data as an asset that I am willing to trade for a service that I see as valuable to me. You (correct me if I'm wrong on this) see your personal data as an asset to protect. Personally, I think both of those mindsets are valid and worth consideration.