Students who already have the knowledge in some given course, are better served by taking other courses. For example, about one quarter of computer science concentrators skip the first introductory semester. After graduation, Harvard students go in many directions. Some work in small companies, or even start their own. Others work at large software companies.
Some students work in the consulting or financial world.
Some go on to pursue PhD degrees in computer science. One has even tried his hand in professional baseball. Yes you can. Harvard faculty work closely with students on independent research projects. Independent research projects are organized on an individual basis between the student and professor.