Are Grades important?

My parents are uptight about my grades. I have no support just grounding and screaming if I come home with a grade less than a B. I am quite smart, yet p with B's without doing homework. My parents are not happy about me receiving to C's on my report card. I currently got a $24,000 yes, 24 thousand scholarship to a private school. I must maintain straight A's and play Chess(I am a national Champion) yet my parents offer to incentive to get good grades. I am a great arguer therefore my pion becoming a lawyer is profound. My parents are very strict. I am in 8th grade and entering high-school next year.