Don't forget, if the market crashes and AMZN stock gets a 50% haircut, that big pile of cash AAPL has been shoveling their profits onto on can get mighty scary to everyone very quickly.
The problem with the cash pile, and also with other companies' large cash piles, is that a lot of the cash, maybe even the majority, is held overseas. Hence there will be an almighty tax bill if it is brought back to the USA.