I agree with your points in the large, but don't fault the kids. Youthful hubris, especially on the scale you've highlighted here, is ridiculous, hopelessly naive, indescribably arrogant, and... breathtakingly wonderful. That ill-founded self confidence will fail every single time - except when it doesn't, in which case the results are magnificent.

My own optimism is nearly spent, which often leads me to hopelessness. That's held at bay by listening to these kinds of kids talk about their ambitions. Don't worry, they'll figure out it's hard, and in a few years some of them will laugh at their former innocence (or blush at their swagger). In the meantime they'll have swung a hammer a few times at the infinite brick wall. Please don't wish them away.