It seems to me that you are mixing up two questions. One question is why your mentees study things they think are neither interesting nor important. The other question is why people might be encouraging them to do so. For the first question, why don't you start by asking them? I'm not claiming that they'll have perfect introspection; in particular, I don't expect them to admit to 5, but if the reason is 1, I do expect them to articulate that. But I don't expect many people are motivated by 1; that seems more like the answer to why Amy Chua wants her children to do things. And even if the children know that it reflects parental desires, they may not be able to explain the parental thinking.

Also, to the extent that your goal is to explain the survey, in particular the frustration, I think you can rule out 2 and 4 and maybe 3. Those of 2 and 4 would just move on to another subject.

Another way to put the two questions: why do people do this; and why should people do this?