Investors making purchases in an overheated market need to recognize that it may often take an extended period for the value of even an outstanding company to catch up with the price they paid.
We love kitties, gawd bless their little whiskers, and we don't give a damn whether they or we are superior or inferior! They're confounded pretty, and that's all we know and all we need to know!
Certainly we do not need quantum mechanics for macroscopic objects, which are well described by classical physics - this is the reason why quantum mechanics seems so foreign to our everyday existence.