Using Facebook for your need is actually good for us but when we waste most of our valuable time then it becomes harmful. The biggest disadvantages of Facebook is it's addiction which causes many problems, mostly because it kills our precious time. Moreover, Fake profile and ID! Fake profile is one of the biggest disadvantage of Facebook. Now it is easier to create fake profile with a stolen picture. People often use fake profile to insult or harass someone they don't like. Teen girls are more vulnerable to these activities.