if they are paid badly, they will not give their best, especially if they know that additional effort won't be appreciated

Whatever I do in life, I try to do my best and do the best I can. If someone I work for doesn't recognize my effort, after a while I give up and find someone else who will appreciate my effort...
I don't think like "they can't reward/pay me as little as I can work"... still I spend the time of my life and I want to get what my dedication deserves for the time I give (fully dedicated).