I am not using it because I believe “I have nothing to hide”.
I am sensitive to privacy and secrecy. I will fight for it every chance I get.
But I willingly share my life on facebook and enjoy the content shared with me. I get more value out of facebook than the countless other services that spy on me.
For example, just a few weeks ago I got a fake hand written letter from a car dealership telling me exactly how many miles I have on my car and how I should trade it in.
My ultimate conclusion about privacy is that you should take steps to protect with you want to remain private. Because even if facebook disappears tomorrow, something else will take its place, including things created by our own government.
It's sad to think that, but it keeps me from naively thinking that what I share online is somehow private... because it's not, and never will be.
That includes places like HN and Reddit. The government has programs to monitor all our profiles on these sites. I am aware of that, and I live my life accordingly.