Why do I care about things that don't concern me?

I seem to get bothered very easily these days. Work has been stressful, and it’s hard when you work super hard and someone in a different section (but same area) has barely anything to do daily, so they laugh it up all day and kiss butt to their supervisors, so they think their worker is a “star.”

Everyone knows co-workers know how people REALLY work, rather than their supervisors. I don’t know why it bothers me so much, especially when I hear the person praising themselves and talking as if they’re the best employee on the face of the planet, when it isn’t nearly true. They’re irritable, un-empathetic and not supportive of their co-workers.

They will pass on work to me, and it makes me angry every time since it isn’t MY job – but nothing ever changes, seems the people above them only look out for their team.

What do you suggest I do? I try to not get angry but I really dislike hypocritical people. I know I can’t expect them to be like me, think my thoughts or do my actions, my expectations and attitudes are different. It’s just… hard.