You should have the ability to write 20-30 pages well structured text to show that you can think, organize your thinking and communicate your thinking to others in your field. Many people graduate without this ability, but at least they have had some practice and can write 5 pages better than when they started the college.
You should know about the things in your field even if you don't master any of them yet. Being smart but restricted is not substitute for college degree. For me the value from higher education came from mandatory classes where I had to learn stuff that I was not particularly interested in. I was interested in algorithms, machine learning and low level programming. I would have never studied database design, computer networks and software engineering as methodologically on my own.
You can avoid learning most of the above when you go to college, but you learn at least something. If you don't have a college degree, you should try to learn on your own. You should have completed large projects that you can demonstrate your grit. In many ways college degree is showing for others that you can delay gratification enough to graduate.