I remember the good old days of web-browsing, when I'd just zoom around the internet without a care in the world. The first time I got a small whiff of something foul was in college one day, when a professor yelled at the class because someone was using telnet to connect to remote machines. "Are you crazy? It sends everything in plaintext! Use SSH!"
Then eventually I put together a website where I had access to the server logs, and oh boy, it was not fun reading those the first time. Line after line of bots in Ukraine, trying to access vulnerable scripts that may or may not exist on my server. Then I checked some of my SSH logs, and saw the same thing. Thus my innocence was destroyed forever.
One day I read on Slashdot about Flash cookies. So I had a really bright idea:
ln -s /dev/null ~/.macromedia
That'll teach them! No more flash cookies. (Note, don't do this if you like watching Flash movies in your browser. They stop working on certain websites. Annoying. Next best thing is a plugin to let you delete them.)
The bad thing is that I still don't know very much about network security and privacy. If I knew more, I'm sure I'd worry more. On the other hand, if I was a locksmith, I might feel bad with the quality of the lock on my front door. And yet my house has never been robbed (yet) and my computer has never been hacked (yet). People tend to worry about what's right in front of them. Maybe what you don't know can't hurt you.
But I still cringe when someone sits down in an airport or a Starbucks and logs into their bank account or work email.