If you think you are private and secure then think again. Do you use a smartphone? Do you use Google ? Do you use Facebook ? If yes, your privacy has definitely been compromised. Your data might also have been leaked in one of the many data breaches throughout years. Every time you turn on the location of your device, every time you give google permission to your device's sensors it's collecting some data and sending it to google's servers. Your data can be used by many ways by these organizations. For giving recommendations on YouTube that you might love watching to selling you products that you don't even need.
Have you ever had a conversation around your phone about 'something', then later saw an advertisement on Facebook or Instagram for that same 'something'? Trust me it isn't coincidence.
Google employees can even access users' email to delete virus', or remove potentially unsafe or violent emails. Emails are considered as one of the most private medium of communicating. Guess what, Google employees can access that without a warrant. All comes down to that one part where you have signed the agreement clause when you created your account.
On his blog by David Evenden he says, " I would nearly guarantee all email vendors are the same way. They'll say they can't, they'll say they don't...but trust me...they can and they do."
Basically you are being sold to companies without even knowing it. Your info brings money to them. How else do you think free to use services companies like Google, Facebook, etc earn money? I am not a security expert but I can say that I have done a good amount of research on this issue. Nothing is free in the internet, your information is more valuable than any form of money.
There is a lot more to this problem, this is just the tip of an iceberg. Privacy is the main currency in today's world. It's up-to us how we choose to keep our information. Just knowing this may not change your daily routine about how you use the internet but you'll learn what's happening behind the bars. Some of the things mentioned above maybe very difficult to implement. But that's the cost of privacy ; you need to trade some convenience.