Answer:
Using such social networking websites is quite helpful in finding friends, being socially active, being aware of different occurrings around the world, and also at sometimes educational; whether it be in life or academically.
but the problem arises when you don't use those ''sites'' for which they are intended to be used for, like uploading private stuff or talking or discussing about wealth or relations with others.
criminals can use such sites to meet up or come in contact with easy targets or some real boasty people and make them fall for their traps and false schemes.
also authorities can use those sites to find or uncover mysteries connected to crimes or misleading cases.
Using such sites can be good as well as bad, its about how the see the world or how they want the world to see them...