I know where you are coming from with that John Nash link example, since I am a mathematician myself too. That's exactly the Math Utopy when we scale up the numbers of our clamors to levels of: "Minimum 90% consensus between all humans" along your whole post.
The family, Family with Kids, City, Country, Globe... ¿Notice the Unpredictable HUMAN factor on that equation?
Going through a simple & pure Logic Reasoning to reach that 90% of consensus, which you are proposing here, when dealing with such Quantum Brainy Creatures replete of immensely diverse and different upbringings, interests, circumstances, wishes, yearnings, goals, etc, etc. ¿Does that not tell you anything about this mathematical fallacy?
Take our debate like a sample. We both are scarcely two of those Quantum Creatures trying to reach consensus. Now scale this up to the numeric levels of tiny clans, sects, little tribes, communities, a whole village, cities, bigger societies, countries, continents or the entire planet like you imply. Oh boy! even try to reach a merely fifty-fifty percent of consensus at such high amounts of multifarious termites, we will need to define before if we are talking about waves or particles in first place. ;)