In this age of information overload, there is a 'know-all' illusion. You probably don’t know as much as you think you do. The convenience of a personal computing device is only a click away to lift the veil of ignorance, though. If information is in public domain with quick and easy access, why are people tested for how much do they know? Why can't ignorance be evaluated instead? Let knowing less of more be the dictum, because ignorance is a bliss!
After all, how much one must know? Aren't there things that we know we don't know and there are things we don't know we don't know. That's to say, there are known knowns as well as unknown unknowns. Rarely, if ever, there are unknown knowns. A bit convoluted but in reality it is simple. In the words of Socrates, 'knowing that you know nothing makes you wise'. People have stopped burning themselves out on knowing everything because they don't know how much they must know (as also electronic access to all that one doesn't know).
No surprise, therefore, that one in four Americans don't know that the Earth revolves around the Sun. Is it a big deal? Neither does the Earth need an acknowledgement for it's stupendous efforts nor will it stop obliging the mortal earthlings for its untiring efforts. Why must everyone know what the Earth does? If most of us don't know how an aeroplane flies why must we care to know what the Earth does. It is no more than a matter of civilized delight to know how things work. No more, no less!
A majority neither knows nor does it need to know how they make Coca-Cola. The fact that it tastes fine is a perfect substitution for not knowing what the ingredients are. Even if we were to know the ingredients, would it make any sense to us? Anyway, we don't seem to care because half of us are affected by illusion of explanatory depth, a psychological disarray which propels us to claim that we know things while in reality we don't. It is our existential crises.
All said, one of the most terrible feelings in the world is to know that someone else doesn't like you. It is a known known that one would not want it to remain known. Especially when you don't know what you've done to deserve it. It is for this reason that I think there are some things that should be kept secret. You never know which 'secret' of yours will make others develop a disliking for you. Reason enough that I don't want people to know what kind/brand of underwear I like/wear.