The idea that a kid can't play without some tangible end goal of employment is what's gross. Not the activity, or the underlying discipline (engineering, in this case).
Much more gross to end up doing something they don't like because they never got to try it out...
There's nothing wrong with turning something into a career, but turning every action into career chasing is saddening. It's pretty gross to leave kids thinking they can't just enjoy something without juicing it for cash.
If they try a hobby for a while and give up on it because they don't enjoy it enough, then yes. That seems like a reasonable definition for "failure."
Nothing wrong with failing - in your career, hobbies, relationships, or whatever else. Sometimes EQ means recognizing that you should stop beating a dead horse.
There's more to life than a career.