Why don't we see quantum weirdness in everyday world?Watch
Well as I understand it these sorts of things could very well happen at the macroscopic scale, the probabilities are just unimaginably small at the associated high energies.There's a little thing called the correspondence principle which basically states that quantum models must mirror classical models at sufficiently high energies. I would elaborate but I don't want to risk letting anyone know how little quantum physics I actually know
You are correct in your basic assumptions about quantum mechanics and it's perhaps best to look at systems as many simple quantum mechanical systems. Each system has a small probability of being something (an observable to be precise here). If you think of adding more and more systems and consider the average or (expected) value of the system, it eventually reaches a stage where it reaches a limit. This, is what classical mechanics is revealed to be; working with the expectation values of systems.