Let's define crazy as an inability or refusal to define and adapt to reality.
At sunrise on the Serengeti Plain, reality for the wildebeest is that he must run faster than the lioness...or he is dinner. And the lioness must run faster than the wildebeest or she cannot feed her cubs or herself.
In the wild, if you are alive...you are sane.
But human beings are able to exist at quite some distance from reality and, the more society and families coddle their members, the more such members are able to extend that distance.
Human insanity, quite incorrectly, has been historically defined by society and families as that distance from reality at which members become difficult to handle or inconvenient. That of course is a fallacy.
Because humans cannot define reality (and, for the most part, refuse to try) and because reality, even if it could be defined, is a rapidly moving target, it is difficult to calculate the distance between a person and his reality.
But knowing humans as we all do, we can be safe in presuming that such distance is, on average, significant...and that humanity is collectively and individually quite insane.
Thank you for your contribution. I hope you had fun writing it. Now, for the rest of us, would you mind relating it to something real? I like to compare my reality to something real so I need an example of what you are describing. Thank you, again.