@PerfunctoryPeter, I was also surprised with my waitlist due to my scores and extracurriculars. I definitely don’t think being an upper middle class white male helped me, and your background probably didn’t help you either. I also got rejected from MIT as well. I guess we can just hope for an extremely low yield.
Originally, I thought that not taking the ACT could have affected you, however it appears many people got in with not as great test scores, so that doesn’t seem to be high on HMC’s list of grading.