I think what separate the great daring acts from mere stupidity are two things: intelligent planning and the ability to achieve the goal.
Regarding intelligent planning, one must know what one wants to achieve or else everything is an opportunity, and time and effort are not managed well resulting in too much waste. A definite goal determines what is important and what can be given up if necessary. Though the road to great achievements is sometimes paved by luck, half of the time it is paved by determination. They alternate, sometimes one is longer and sometimes shorter; but one thing is for sure: they like making the story of one’s achievement exciting.
Regarding the ability to achieve the goal, one must be true to oneself. While this is not always easy to know for there are no exact rules in determining whether one is without talent or how much hard work one needs in case there is a lack of talent, I think the truth soon makes itself plain after one too many tries and the universe still does not respond with the desired outcome. To lower one’s expectations or to try again? Nobody said that human life is without anxiety. Then again, there are the truly idiotic examples, say, of gung ho rescuers who have absolutely no training rushing to prove they can also be heroes.
That said, objective observers consider all daring acts as examples of idiocy. It is when they succeed that they are labeled courageous.