> It does not really even indicate aptitude in the discipline. I don't know what standards are like in the U.S., but at least where I went to university a good

> It does not really even indicate aptitude in the discipline. I don't know what standards are like in the U.S., but at least where I went to university a good 30% (of those who were in the top 20% of the highly selective entrance exam) ended up getting kicked out because they didn't pass enough courses in their first or second year. Yes, for some people it was an inability to concentrate, but I also know a few who put in more than the minimum hours but for some reason it just didn't 'click'. I don't know if the US is suffering from grade inflation which lets through people who should have been failed, or if you are just in a bubble of people who are successful, but what you describe is nothing like what I experienced.