Jackie Evancho is a 12 year old child with a Sony recording contract for doing classical crossover albums. Her dreams have come true in part because she worked hard to achieve them--but all that hard work would have gotten her nowhere if she was born with a tin ear and a wispy voice.
It takes both gumption AND natural talent.
My objection is to encouraging kids who aren't going to get there no matter how hard they try because they weren't born with what people like Jackie was born with.
We should all have our dreams, and our parents should have helped us realize the realizable ones. When our parents give us dreams we can't achieve no matter how hard we try--and which we try to achieve instead of working of what we actually can accomplish--then like Simon Cowell I'm the one being kind to tell them the truth and you're the one being cruel, by setting them up for a fall.
It is true that nearly everyone who has achieved great things has had people who didn't think they could. Every best-selling novelist has a shoebox full of rejection slips.
But it is equally true that everyone who reached for something beyond their grasp also have the equivalent of a box full of rejection slips--only they reflect reality.
We should all pray for the discernment to let us encourage everyone we meet to achieve the dreams they have or could have or should have...that are realizable. OTOH we should also pray for the discernment to not encourage dreams we know are hopeless.
That's one reason why I've never wanted to teach a writing class. I'd have to tell most of the students to write journals but don't try to publish anything because they can't achieve that.
You shouldn't be cruel to people whose dreams you know will fail. And you can take the easy way out and just make polite noises when they're obviously begging you for encouragement in their Quixotic quest. But you'd be kindest if you Simon Cowell'd them.
It's not the adult's job to be the child's friend. They have friends their own age. It's your job with children to at least be the guide on side if you don't wan to be the sage on the stage. But steer them toward the spot where the fish are. Don't give them a bum steer.
EDIT ADD: When I did my student teaching in several grammar schools, my instructors told me I taught 3rd grade as if it were 4th grade, 4th as it it were 5th, and so forth. I challenged them and stretched them, tried to find what they were capable of. I was both demanding and encouraging. I just never told someone they were something they weren't.