Problematic student at a very high level
The best way to deal with this kind of student is to head it off at the pass.  If you can get the student at the beginning, you can often prevent the problem from festering in the first place. I have a student coming in next year who I have already been warned will have this problem, and I plan to show this to my class on the first day:



I will then say something like, "For whom is this situation unfair?"

When the kids point to the fish, I will point out that it is just as unfair to the monkey.  I will then ask them to talk to a neighbor and figure out why.

I will finish up by saying that I have a promise for the fish of the class: everyone who puts in the work will be able to climb the tree.  That's MY job.  However, I have to find a way to be fair to the monkeys as well.  That means that I must reserve the right to try to find ways to push them to get better in my classroom.

If they are in that position, and can get the work done very easily, and find that I give them harder work, I ask a few things of them: (1) understand that this is fairer than it may initially feel, and (2) understand that this comes from a place of actually caring about them as people. Making more appropriate assignments for them is harder for me as well. If I didn't care about them as people, I could just let them get away with the minimum.

In essence, then, I am trying to recast making differentiated, harder assignments into something that the students will understand as both a loving act, and one that respects them deeply as individuals.