The advice given is great and certainly worth your DS's time, but he also should be realistic about waitlists at IVY's. Admission from the waitlist is rare. He can check the school CDS for historical numbers to get a feel for the odds. For example in the 2019-2020 admit year (the last pre-pandemic year), Princeton offered spots on the waitlist to 902 applicants. 668 accepted. 1 was admitted. It's the bird in the hand vs. one in the bush dilemma.
100% agree. DS waitlisted to Cornell, ND and UMich. It's not just Ivies: UMich Fall 2021: 13,149 applicants accepted waitlist offer with 0.5%, or 69 applicants admitted from it. He's also an engineering major waitlisted to college of engineering- another needle to thread. DS did not except any waitlist (USNA would be the only exception if offered- as those numbers make more sense and do not keep him from moving forward with alternate plans). Something to consider when you're trying to plan out the next step.
IMO you are going to need to decide if you want to do AROTC (at Georgetown) or roll the dice at Harvard or Yale. Having someone else (the US ARMY) foot the bill for tuition will make little difference to Harvard or Yale with each endowments > the GDP of 100+ countries. Looking at the CDS from 2021-22 at Yale you will see that 1030 applicants were offered waitlist slots. 774 accepted. 4 were admitted.
