<p>It’s possible to be accepted by a school but asked to do a lower grade than applied. Highly uncommon, but it happens. Depending on the ‘prominent’ school OP has in mind, EVERYONE coming in could have great grades/quals/ECs.
An expensive whim? Most of the fullpays consider $50k chump change.
An alternative for the OP would be a gap year between high school and college. There’s no particular reason to rush into college, especially for boys (dunno if the OP is a boy or not).</p>