How naive is the average person? The purpose of facebook is to gather this information, hence why its offered as a "free service".
Frankly, I don't understand why the stock is going down, facebook is fulfilling its core mission: Get private information on millions of people and package that information for sale to its clients. If anything CA situation should show how FB is fulfilling its core mission.
The fact that the public is now waking up to this is not a breach, its simply casting a light on what has always existed.
The public waking up to this breach and the costs being exposed are probably a huge part of why the stock is dropping. Facebook's continued profitability and success is dependent on its users not understanding how their data is being used. And now "everyone" knows, so the secret is out and hopefully Facebook can't get away with this going forward.