Envy...harmful feeling

I m still confused...Y people having envy feelings....Y we cannot stand with other happines..y we are so mean? Never got the answer for the simple question y people feel happy when others do not do well...ain't we statisfied with what we are having? Y we look at others...y we compare ourself with others...? If we stop doing or feeling all this things, if we stop giving importance to others works we will be fine...what the hell they are for us...we are to do our best...n I know I m doing my best....