[fiatmoney]

If you simply conflate "richest" with "most powerful", this is already the case, and has been for most of human history. It's unclear why we should care about monetary wealth specifically more than other dimensions of power.

[chiaro]

Probably because it's very easy to measure, and correlates with other dimensions through well known adjustments like Purchasing Power.

[jessriedel]

Money and assets are more easily measured, taken, and transferred.

[dkarapetyan]

It's easily measurable and since everything pretty much correlates with everything else when it comes to complicated systems like the world economy putting in some corrective feedback is a worthwhile effort. As it is I think things are stuck in a positive feedback loop (rich getting richer) and that's not healthy from either social or systems perspective.