besides spend it on frivolous shit like yachts and planes and stuff, there's no way it's all liquid. do they just park all their billions in a bunch of investment vehicles and wait for it to propagate itself? don't they get bored of just waiting and watching line go up?
Nothing really at all. They reinvest it to accumulate more, as another poster pointed out. The majority of it is set up for their kids, grandkids and further family down the road to inherit all of it and live comfortable lifestyles.