Money. There isn't much you can't buy with it, except time of course but it does seem to make the world go around. I've particularly noticed it since I've been unwell, one of my chemo drugs is so expensive that I can only have 4 sessions of it maximum. And I know in certain countries healthcare is very expensive. Literally everything seems to come back to money
Out of those two options probably time. Money defiantly makes the world go 'round but everyone will run out of time eventually. We all die with time, and money can't do anything to prevent that.