My fault?!

Today my student's mom told me her child had a very big pressure in learning English. She employed me as her child's tutor, she thought I'm a good teacher to teach her naughty child. She was also sorry to me that she knew I was very patient to her child. Although this is a compliment to me, she still let her child give up his English. I think my student is spoiled by his mom, so his mom doesn't want to continue it. Probably, it's a good news to me because her child makes me mad all the time. Everytime when I see him, he just wants to play computer games and doesn't want to do homework. His mom doesn't care about his English, either. I was depressed that his English didn't progress. Someone told me there is no stupid student but a unprofessional teacher. When I heard it from that person, I was so angry. If she thinks I can't teach them well, how about her? Is this my fault?...