>Young people in general have more energy and more stamina. They are faster. I think this is biological fact. Quite often they do foolish things, but this is probably overcome by the increased capacity to do. The flexibility. The lack of jadedness. The ability to get excited. The ability to be directed.
>There's a reason the military only accepts younger people.
Sure, they are of course more fit and superior in anything "physical" (which is actually a large part of what a soldier has to do), more resistant to fatigue, long hours, etc. and usually much less prone to (say) ilnesses, backpain, or any other even slightly imparing condition BUT - not so casually - they are introduced in a very rigid schema with a set of very narrow rules and usually with a sergeant major shouting at them as soon as they even think to do anything minimally outside the said rules.
From the outside it seems to me like putting together a bunch of people in the early twenties with no or little rules and no strict supervision/discipline, while undoubtedly a "creative" environment tends to resemble more a uni fraternity than a business place.
I am just guessing, of course, but if you are over 40 and you started working 20 years ago or more you most probably started working in a place where there was a "dress code", some strict work times, a manager twice or more your age that would tell you what to do (but also possibly help you advising how to do it), some more experienced colleagues , etc., in other words some form of "forced" discipline and of mentoring.
And now I will introduce (being over fifty myself, so somehow self-qualified for it) another concept, seniority does NOT mean in itself experience, experience is the SUM of seniority with the attitude to learn, discuss and extract useful lessons from all the things that happened during the (many) previous years and be capable of adapt what was learned to changes that inevitably happen ove the years (be those changes in Law, society or technical matters).
I know quite a few people my age that notwithstanding having worked (often with some financial/personal success) for many years, learned nothing, i.e. are nowhere "wiser" than they were when young.
Experience leads to be wiser, seniority leads to just being older.