Yes, I am one of those 21st century people who tries not to use facebook for a wide variety of reasons- my relatives have it, it changes formats once it has found something that works, it doesn't hold my attention long enough, lots of my Japanese friends don't have it, etc...
But the main reason I refuse to use it is because it tracks what you do. Facebook has admitted to, "keep[ing] a timestamped list of the URLs you visit and pair it with your name, list of friends, Facebook preferences, email address, IP address, screen resolution, operating system, and browser," while you remain logged in to the site and, "captures [capturing] everything except your name, list of friends, and Facebook preferences. Instead, it uses a unique alphanumeric identifier to track you," when you're logged out (Here's The Information Facebook Gathers On You As You Browse The Web). However, it claims that this is only for sites with the widely-recognized "like" button that facebook attaches to just about anything it wants to. This information is then distributed to, "...third-party app developers," similar to how supermarket cards (if you've ever shopped at a grocery store overseas & joined their rewards program, you'll know what I'm talking about) collect information about you based on what you buy, then promote certain products they feel you'll be interested in (I'm sure I sound like Fox Mulder by now...Soon the aliens will come and force feed us little food capsules based on what we get at the supermarket, etc...) (Christopher Soghoian in How Much Should People Worry About the Loss of Online Privacy? and Supermarket cards
threat to privacy?).
However, it's not just advertisers I'm worried about when it comes to facebook. Any government that claims to give its citizens freedom of speech, yet has contractors that go into groups that oppose its policies in order to eliminate them is no longer providing its citizens with freedom of speech. According to NaturalNews:
"A secret campaign to take out groups and organizations that oppose the policies and agendas of the US Chamber of Commerce (USCC) and the US government has been outed, thanks to an archive of private emails obtained by Think Progress. According to reports, USCC hired HBGary, Federal and several other defense contractors to create fake accounts on social media sites like Facebook and Twitter in order to sabotage progressive groups critical of the organization's platform"(Exposed: Military contractors hired to create fake Facebook accounts, infiltrate opposing groups
I'm not saying that I'm fearful of what the government does as a whole, but rather what it does in order to achieve its goals. (I really sound like Mulder...Sheesh.)
I guess the best way to summarize this, as well as to warn you about what you shouldn't say on any social network, would be:
"You wouldn't be surprised that a rock concert is loud, or that a swimming pool is wet, so don't be shocked when you learn that a social network shares data. It is better to assume that anything you post on a social network may one day be public, and think carefully about posting that rant about how fat and lazy your boss is no matter which group you think you are sharing it with" (Facebook and Privacy Don't Mix Well). Watch what you click + what you write, having that end up in an advertiser's, or worse, your boss' inbox, isn't a good thing.
Final exam question: How can you remove your personal information from services such as facebook? (Answer: More about your online privacy)