The thing is, the cost of discouraging the wrong kid -- the one who ends up curing cancer or otherwise innovating in an extremely useful area -- is unbounded.

The cost of encouraging the ones who fail can be heavy, but at least it's finite.

And it's not always obvious if "their performance already clearly shows they aren't going this route." The Nobel archives are full of acceptance speeches that describe how the recipient got off to a slow or unpromising start.

> The thing is, the cost of discouraging the wrong kid -- the one who ends up curing cancer or otherwise innovating in an extremely useful area -- is unbounded.

> The cost of encouraging the ones who fail can be heavy, but at least it's finite.

Assuming that every kid has a non-zero chance of being the "right kid," then discouraging only one child results in infinite cost and so every child should be encouraged to try to cure cancer...