I'd argue that this is simply a matter of the nature of money and investments. When you're a regular Joe cashing a paycheck, the numbers on your bank account seem like absolutes. But on the scales that large companies operate, things are a lot more fluid. For instance, banks don't have direct access to all the money their account holders have deposited, the exact value of a large investment is subject to all sorts of market conditions, inflation and currency fluctuations changes the actual value of things over time etc. Even if you look at the economy of a single person, this phenomenon becomes apparent.

Remember that "reported cash balance" is just a number. The actual assets backing that number can always be tracked down somewhere.