If HYPSM reject, say, 65% of students w/ perfect GPAs and SAT/ACT scores, that means 35% get in. That's good odds, no?

This is basically a correlation/causation discussion that suffers from the absence of dependable stats supporting the correlation argument, but that’s because holistic admissions processes depend on a lot of qualitative factors that aren’t readily disclosed or easily quantified, as others have noted.