Karma...Friend or enemy?

Do you understand karma? It is so complicated, when you see how people who has been mean at you, hurt you, and hurt others like if it doen´t matter...

And you keep being nice, or at least what you think is nice, and nothing change, you don´t see how your life chenge for good, meanwhile, them those bad people are just so happy, looks like, if you are mean everything will be as you wish... Is it like that? Or is just a matter of time?

I get nothing, I understand nothing... I just hope that justice will come and put everything and every person where has to be...