Why do people troll others?

People troll others in an attempt to goad them into "raging", or making them mad. internet Trolls get self satisfaction out of making other people angry.

This can be done in a wide range of ways, simply by playing stupid, saying negative things about individuals via public posts on the internet, e.g. Twitter attacks on celebrities, or even going as far as to make fun of the deceased, "An Hero" being a notable example, and providing misinformation, as are currently popular with YouTube trolling videos in the gaming community.

Troll people are always be sick. Sign of mental disorder. Why do people troll to other because such persons are insane. You can not expect some thing exude .
Such a sick people feel pleasure to troll others.