I’d say it’s more that high endowment per student colleges tend to have low acceptance rates. With a high endowment per student, the tuition tends to be a relatively small portion of revenue. And high endowment per students tend to be among the lowest acceptance rate colleges. For example, HYPSMC are among the top ~7 highest endowment per student colleges.
The outliers often have strong additional contributing factors. For example, College of the Ozarks has a low acceptance rate primarily due to fulling crediting tuition via work/grants, so net charge to students is $0 for tuition, rather than the usual things associated with high endowment per student HYPSM… type colleges.