How can I deal with pressure my parents put on me?

I’m a 15 year old rising sophomore in high school. It has always been my dream to go somewhere like Harvard or Stanford for college. I am reasonably smart, and I work really hard, not just in school, but in sports, fine arts, etc. But my parents always try to “motivate” me by telling me, basically, that I’m a piece of shit. I’ve tried to tell them I am self motivated, but they just tell me I don’t work hard enough.