<p>In college admissions (and life, probably), motivation, and not necessarily extraordinarily high intelligence, can get you very far. The kids you met at D/M probably went out of their way to join lots of extracurriculars, study for tests, do their homework, and review for the SATs in high school. They probably had decent essays and teacher recs…maybe they were hooked for some sport. </p>
<p>The people you met, however, are probably just a subset of the actual population, although that subset is probably a lot smaller at schools like Columbia, UChicago, etc.</p>