why r there so many people mad at the world?

Answer 1

Because they perceive that the world hasn't given them what they want,when actually it's themselves that they should be mad at because they haven't worked at and earned what they want.
Usually,nothing is easy, you must strive to better yourself. No one can do it for you. You only have the moment to do it.

Answer 2

because they are mad at themselves and they project that anger towards the surrounding world

Answer 3

I suppose that people have dumped on them very badly or they have not been able to achieve their goals in life.