Why does my mom think I'm so stupid?

I'm not being conceited or anything, but I am not stupid. I'm going to a prestigious private high school next year (9th grade) and I went to a private middle school before. I got all straight A's before and I'm on the honor roll. My mom saw my report card and that I was on the honor roll. She talked to all of my teachers and they all said good things about me. Yet for some reason, my mom is still convinced that I am an idiot. She thinks that the only reason I got accepted into a private high school was out of pity, which is not true. She is convinced that I will fail high school, never go to college, and end up working at a fast food restaurant. She even threatened to make me drop out of high school and "get a head start on my career" of working at McDonalds since it is "impossible" for me to achieve academic success. Oh, and since I need to "improve my math skills" she signed me up for KUMON. Yes, Kumon, which by the way, has ruined my life. I'm on Level J, so I am supposed to be two years ahead of my grade level, and yet my mom still thinks I'm stupid.