Because your apathy (well, not yours in particular, but of all the people behaving/feeling like you do) has an effect on everyone. Imagine if most people would be active in demanding their privacy be respected instead of just a minority.
I find your rhetoric of relaxed indifference "I don't care much about X reading my mail" very similar to the "I've got nothing to hide" rhetoric. It pisses me off because a couple years back when everyone was grilling me about not wanting a facebook account and me mentioning all the privacy implications, their response was: "oh, I have nothing to hide!" but at the same time they didn't feel like sharing with me their computer password.
Finally, in 2008 when I was looking to buy an apartment I had to pay the inflated price just like everyone else. It didn't matter that I paid cash. Why was the price inflated? Well, because people didn't bother to care much for the price of the apartment as long as they could get the loan from the bank. I had a friend that wanted to buy a house and all he could think about was what to do to be able to take the highest loan he could get. Never mind how he was going to pay for it later. Fast forward a couple years and now all those who bought apartments with the bank's money are looking for my sympathy because it's so hard for them to pay their mortgage and the bank might take their home.
I wish there was a country for people who cared. I'd move there.
