Let's say you've got $100 million. You want to do whatever you want to do. It turns out what you want is to buy a certain beachfront property. Or perhaps curry the favor with a certain politician around a certain bill. Well, so do some folks with $200 million, and they can outbid you. So even though you have tons of money in absolute terms, when you are using your power in venues that happen to also be populated by other rich folks, you can still be relatively power-poor.
And all of those other rich folks know this is how the game works too, so they are all always scrambling to get to the top of the pile.