I left my first job to go back to school at age 30 to learn science. It was very clear in my second go at University that our education system selects for obedience, not for learning. Ironically, it's the disobedient students who tend to be more creative thinkers, which is needed to be a good scientist. So you see a fair number of successful scientists who had bad grades through college, but just good enough to get into graduate school, where grades are no longer of consequence.
In the States, the career path to becoming a medical doctor selects for high grades throughout, so I had a LOT of classmates who were solely motivated by the prestige of being a doctor. They tended to be completely uninterested in the science (as evidenced by a majority of them thinking that organic chemistry was a "hard" class). I fear the day I awake in a hospital bed to see one of their faces.