[freiherr]

What people know is just practical knowledge of their immediate surrounding and a bit of theoretical models of what is outside. If by "knowing what they are doing" you mean deep understanding of everything from the big picture then it's impossible. Doing your own local stuff as good as possible is the best we can get and it usually works reasonably well. Until we get a dictator in an information bubble, but well that's just life.

[lbriner]

That's not quite true. There is a difference between e.g. making a really nice design "as good as possible" but producing something that is not best-practice, doesn't solve the problem well, isn't a standard look for whatever it is that you are designing.

There are many people who at least think they are working hard and well but the piece that is missing is the context that the work needs to fit into and the ability to evaluate it. There are a gazillion different ways to do marketing (and to do it "well") but most of those will either have little or no effect in a certain context so the true person who knows what they are doing knows the landscape, knows the costs, knows the trade-offs and knows how to measure success.