I dont understand some people?

Like everyone else in the world...I go through life's ups and downs but I know how to learn from my mistakes whether that's a previous relationship that has gone wrong, an essay assignment I got a C on, a job that didn't pan out the way i envisioned it or ext. For me I try to turn the other cheek and forgive people as well as helping individuals in this world to working hard myself and excelling and achieving my goals or capitalizing on my weaknesses. But here's the thing I don't get, there are alota people I have come in contact with who are soo jealous of me for some reason that they'll bash me in any way shape or form or like to see that i fail in life...why? If I'm a good person at heart why would someone act a person like that =s