On the other hand, if you don't tell them, most of them will come to that conclusion anyway. Then they will feel just as depressed, but also alienated from the oppressive adult caste.

I find most avoid considering the question.

Something like that, yes. What I had in mind was mostly stuff related to / described in: Gatto's Lessons and Graham's essay on nerds.

Preparing children for dealing better with the situations and problems described in both of those seems like the best thing a rogue teacher can do for their students, at least at the ages mentioned by the OP. It seems like organized support from the parents, school board, school personnel / other teachers or preferably all of those would be necessary to really achieve more.