To Facebook or not to Facebook

I joined Facebook just because it was just another social network that everyone was doing and it was free and seemed harmless. I didn't realize all the risks of being on Facebook and I never questioned how Facebook made its money since everything is free to use. I thought once you blocked something from someone to see was a great way of using security on a website but I didn't even think of the fact that once something is posted online it's there forever. It's just opened my mind to it all.