Actually, there are several reasons.
One is that they just put it into overseas tax shelters, meaning that the money is doing absolutely nothing except propping up the finances of playgrounds for the wealthy. Another is that they put the money into buying elections, so that they can keep their current tax cuts and get even more of them.
But, I've just discovered another reason: they waste the money on preparing for the Apocalypse, failing to realize that, in a true Apocalypse, their money won't last very long. In an end-of-the-world scenario, scarcity would create price gouging beyond belief. A simple bottle of water could cost millions.
And, in the meantime, people around the country do without the most basic resources. For them, it's already a world in which a simple bottle of water might as well cost millions.
Can we somehow get past this idea that the rich need to be endlessly pampered at the expense of all of us? At the rate things are going, we're being propelled toward the Apocalypse--and we don't have to be.