I don't think there's anything wrong with the mantra. But the "this" you refer to doesn't really illustrate a problem with it.

Here's how these exchanges SHOULD go ...

    Kid: Could I do extra credit to bring my grade up?
    Teacher: No, I'm sorry, the grade won't change.
    Kid: Okay.  (thinks to himself, "Well, it was worth a shot")

The unhealthy thing is not the venturing to ask. It's not accepting a reasonable answer when it is given:

    Kid: Could I do extra credit to bring my grade up?
    Teacher: No, I'm sorry, the grade won't change.
    Kid: How dare you.  You'll be hearing from my parents.

(or, more likely)

    Parent: Could my kid do extra credit to bring his grade up?
    Teacher: No, I'm sorry, the grade won't change.
    Parent: How dare you.  I'm going over your head.