I have, and it was because I didn’t try. I thought I was too cool to do the homework assignments and the majority of my grade was on the homework assignments.
People also have different learning styles. I’m absolute garbage at memorizing things through flash cards. With traditional lectures I memorize it long enough to brain dump it. I remember things better through hands on teaching. If I have something where I can actively participate in I can not only learn it, but also have something to memorize it through.
At my job, we have different ways to teach people how to do our job. We have some people where you can hand them an instruction manual, leave them alone, and they can figure it out. Others are like me where I have the instruction manual, and someone there to help me drive, and I can learn how to do it after multiple attempts. The only people who had issues learning the job were people who would just sit there and whine because it wasn’t a quick and simple process.
So unless you have a legitimate learning disability, it’s all a combination of motivation and finding the right learning style for the person.