I myself worked during my studies, classes were from morning to late evening, so I could only work on weekends and nights. I know that if I could just focus on studying and workshops - my skills would be incomparably higher.
Except that I studied sculpture. If I make a rubbish sculpture or a lousy drawing, I can only offend someone else's sense of aesthetics.
But think of people who study medicine, psychology, social sciences, civil engineers. In such cases, lack of knowledge and qualifications can cost others their health or even their lives. This is what scares me the most.