[beej71]

I think we're getting closer to the actual situation with this description. There are a lot of buckets of people who don't do well in a particular class.

And we both admittedly don't know the size of the bucket of people who cannot, given a lifetime of 80 years continuous study and tutoring, understand a topic.

But in my teaching experience, it's dwarfed by the group of people who doesn't care about the topic and bombs because they don't put in the effort.