I hear "I don't have anything to hide" all the time, here are my typical responses.

1. do you want everyone to know about your illness, divorce, insert really personal thing here
2. when the time comes that what you like/follow becomes outlawed, where will you hide?
3. you don't have anything to hide, but I do (siting the above two statements) and if "they" can get to you and leverage something you chose not to hide in order to get to me, we have a problem.

How the hell did we miss the line that we crossed when we gave up our privacy? we were so blind.