There are some people with whom you cant tell certain things directly. They use social media as tool to convey their thoughts. But on the other side some people who in seek of attention upload sad post. whenever they are worried and expect others to ask about their problems. They post anything to get attention.
Some express there happiness like posts all good moments which is fine to some extend when it crosses the limit it becomes a problem they will not enjoy the reality. For example if someone loves rain they must sit and feel it instead seeing through camera and posting it wont give them actual happiness of rain.
Now a days its very easy to know about someones personal life as they post everything in social media which may end up in trouble. You can post things but there should be a limit and you must not allow everyone to know everything about you and your personal life.