Why do we as a race of beings wish to harm each other?

i use to be a very bad person due to my life style and where i grew up. i've always suffered many pains from loss and regret. i've been out of prison for 2 years, and i've become such a humble loving person. on april 16, around 3:00am i was at the laundry and i stepped out to smoke a cig, when i was attacked by 16-17 spanish dudes who were coked up.they robbed me for everything i had, and now i'm completely broke with no clothes. all i can think of is bad thoughts. i want to kill, and everyone tells me don't worry, things will get better, but never does. i have only 2 months on parole, and this happens. why? what is so wrong with this world? i did what i did to feed my family, but they did what they did just for fun. i could get them, but i wn't be able to come back from that route. i need a real persons advice please.