Gap year sounds like a great idea.

Regarding worthwhile courses that aren't just a repeat of what you might learn in grad school or working for a company, I recommend taking challenging courses outside your discipline. You may also find some thoughtful and interesting people in the humanities, social sciences, hard sciences, or other engineering departments. Also go to graduate seminars and attend talks. At any university there is usually a continuous schedule of interesting speakers of all kinds as well as cultural events. Take advantage of them.

Regarding CS, I recommend skipping anything you already know and enrolling in upper division and graduate courses. You may also find that adding some EE courses (circuits, computer architecture, signal processing) or ME courses (robotics) into your CS/STEM mix might add some interest and challenge.

Faculty jobs are insanely competitive; this means that at any school anywhere you are going to find basically superstar faculty (at least in terms of their CV.) Go find them and join their labs and research projects. If there is an undergraduate research program, apply for it. Otherwise knock on doors, talk to faculty, put together an independent study course, apply for research lab jobs, talk to grad students, write an undergraduate thesis, etc..

Regarding extracurriculars, you might consider founding your own club with like-minded people, like an entrepreneurship club. Sometimes student chapters of technical societies like the ACM can be interesting and fun. You might also enjoy a musical ensemble, theater production, sports team, outdoors/wilderness expedition club, debate club, a robot or programming competition club, or a hackerspace. Also
"public service" type organizations in the university (or beyond) whose purpose is to benefiting the local (or even global) community can be motivating and worthwhile.

It sounds like you want more high-motivation, ambitious people. You might find them in other majors or perhaps at another school (maybe consider transferring) or in a startup company. Or maybe somewhere you never thought to look - maybe ROTC, or pre-medical societies, or student government, or in the law/medical/business/graduate engineering schools.

At many business schools there are also students looking for a "founding partner" to do all of the technical work in a startup company while they take most of the money for doing the "business" part. Perhaps that person could be you (for better or for worse.)

I recommend thinking of the university as a set of components (professors, advisors, lab facilities, libraries, undergraduate and graduate students, high-speed symmetric internet connections, interesting lectures and events, gyms and athletic facilities, etc..) but it is up to you to assemble them into an education that you find inspiring and worthwhile.

Lastly: talking to faculty is underrated. You may get brushed off by some, but many faculty appreciate cheap labor as well as highly motivated students, so keep asking.

And post-lastly: if you can be the #1 student at your university (and ideally build a research portfolio) you may be in good shape for graduate school if you are interested. It's harder to be #1 at a school packed full of overachievers. On the other hand, some companies recruit primarily from a small set of elite schools, so attending one of them can be an easier pipeline into those companies.