When you post on Facebook or Twitter you are working for free. Facebook makes money serving ads to users but Facebook produces hardly any content at all. The reason so many people are on Facebook is because they are looking at each others content. The more you post on Facebook and get your friends and family to spend time looking at it and the advertisements surrounding them the more Facebook makes. This makes you a digital sharecropper except that you aren’t even getting paid.
This doesn’t mean you should stop using Facebook, it just means you should understand exactly what you are doing there. My suggestion is that you spend more time adding content to your own website where you own the content. Then when Facebook goes away or looses all of your posts you still have the majority of your work.