No mmo has ever created a successful ingame economy because the game prints money when you kill monsters and it eventually undergoes hyperinflation. They end up resorting to huge gold/item sinks and p...
They’ve never done it successfully “on purpose”, but there’s something to be said about creating a range of small, valuable and rare items and then letting the players converge around whatever works. Emergent (accidental?) “monetary” policy is best