I haven't been in a fight with my employer or anything, but it still needs to be said (in case anyone forgets): Your employer isn't doing you a favor by hiring you.
I have read, time and time again, how employers want to make it seem like they're some noble person for hiring you and that you should be grateful. You shouldn't be more grateful than the grocery store should be grateful for me shopping there. They offer groceries and in return, I give them money.
You offer your employer your time and labor, and in exchange they pay you.
Unless they hire/keep you despite having no use of you, for the sake of providing you with money, you have nothing to be grateful for, neither does your employer. It's a trade, not charity.