On the other hand though, could you say that someone's interests are to a degree dictated by their capabilities? It seems to me like the distinguishing factor between someone who is interested in a challenging field vs. someone who is not, is that the person interested often understands the material to a degree that maybe the other person is unable to. For them studying and doing the work may take substantially less effort and thus their interest continues, even when things become difficult.

This is probably why many programmers are uninterested in your chosen field of teaching.

TLDR, isn't "disinterest" often a cognitive bias driven by some subconscious estimation that we're unable to do something?

I think this affects everyone, a lot.