As a recent graduate of a high-ranked uni, this is somewhat true, but i think CS pulls some from IBanking but also from law, general engr'ing, and medicine. I and many others i know entered school thinking about medicine.

While many people in CS that go to FAANG, et. al are high-achievers, most are the cohort of those people interested in science and technical work more than social focused work. Much bigger overlap with pre-med defectors. Also we had plenty of "anti-social" kids, but interestingly they achieved less and were more likely to work at a small regional company after graduating than a SV tech firm.