There is nothing a college teaches you in a four year degree that can't be learned via the internet. The textbooks can be purchased, the skills can be practiced and learned as effectively.

I took an exam as part of finishing my degree called the FE, or Fundamentals of Engineering exam. I could've learned everything I needed for that exam in a shorter time frame and for far less cost if I didn't also need the piece of paper saying I graduated.

The exception is hands on experience, which is not common in typical 4 year degrees.