Why isn't life always fair?

I know it's wrong to snoop but I saw this guys check and he got a raise and I didn't. I didn't look at all but I hate it when guys get more raised then ladies. I told my employer at work that it isn't fair just because I'm a lady. He was like, "Didn't anybody tell you life isn't always fair? This is the working field. So get used to it. Life isn't mentioned to be all sugar-coated and happy." I obviously know that but I just don't think it's fair at all. I told him off. He said, "An employee with a bad attitude....not employed material, ESPECIALLY for a girl. One more peep out of you and you're fired!"
When is standing up for myself going to get me in trouble?
I work Thursdays, Fridays and Sundays. Thursdays and Friday's from 4pm to 7pm. And Sundays from 9-1pm.