What motive would you need beside "a higher score gets me into better schools"? Surely someone smart enough to get a perfect SAT score can figure that out pretty easily.
Late replying, but I readily admit that supportive parents and a school subculture that valued academics were both factors. I didn’t mean to suggest that I single-handedly pulled myself up by my bootstraps. But the SAT was the main path I had to stand out in applications as a public-school-educated person from a rural place you’ve never heard of.