Some of it relates to interest. Easier to learn something you enjoy than something you dislike. Some of it relates to the professor. Some are better than others and some students do better with certain type of professors. Some of it relates to your style of learning and adapting and understanding how you learn. Some of it relates to study skills and time management. Being ADD or ADHD can be a hindrance. That being said, college is not the end all for everyone and not enough kids and parents entertain other options. There are shortages of certain skills that do not require college and many jobs today that require college degrees really don’t need one.