What you learn at school are facts. Your job at school is to accumulate and remember facts and figures. The more you remember the better you do.

Those who fail at school are not interested in facts; or maybe the facts are not put to them in a way they find interesting.

Some people simply don't have a great faculty for memory. This does not mean they are stupid. It means their imagination hasn't been fired up by academic tuition.

People who are conventionally clever get jobs on their qualifications ( the past), not on their desire to succeed ( now and the future).

Not always but in some cases they get overtaken by those who continually strive to be better than they are.

As long as the goal is there, there is no limit to anyone's achievement.