Probably worth pointing out when iq is measured a purposeful attempt is made to divorce the test from prior knowledge. An iq test is not a trivia quiz(knowledge) it is an attempt to measure intelligence. After a certain age, which I believe is lower than 10 years old - before you would care, it becomes nigh impossible to improve your iq. In short, a genius will always be a genius and a dumbass will always be a dumbass and a proper iq test will identify them as such. Sorry but stupid people exist, there is no "catching up". If you are learning iq tests you are invalidating iq tests.
What you are saying though is quite true, *eventually* you should be able to teach anyone most anything. However, if someone is not keeping up with their peers at university then maybe they should start considering the ramifications in a limited opportunity environment. I do not see the point of encouraging people to pursue a field in which they may never be particularly valuable.