How is OP any more likely to regret attending UCSD than to regret attending MIT? Both have excellent CS programs, both have a lot of very bright students (even if the bottom of the class is definitely stronger at MIT), and many students enjoy their experience at either school.
Plenty of “elite and uniquely gifted” students choose a different school for financial reasons; UCSD is a wonderful school that has many students who are “elite and uniquely gifted.”