There certainly are a lot of fools in Charlie and the Chocolate Factory. The children make uninformed, unwise, rash choices, and they pay the price. Their parents, too, are foolish, because they can't seem to handle their own kids. And once the Golden Ticket offer is announced, practically everyone in the world seems to make a fool of themselves, just to have a chance at the prize. Perhaps it's their greediness that makes them fools. Or perhaps their foolishness leads to greediness, because these folks can't seem to think beyond instant gratification. Either way, Roald Dahl is not one to suffer fools gladly, and he relishes the chance to poke fun at their behavior so we can learn from their mistakes.
Those children weren't foolish – just curious. What's so wrong with that?
We'll tell you what's wrong with that. The lesson of this book is that if you don't listen to authority figures, you'll pay a nasty price.