Within just a few years there were large-scale "gold mining" operations set up in China, wholesalers, retailers, "forex" markets, etc... Nearly the entire modern economic ecosystem was set up around a game.
At some point, if WoW was treated as a country, its "currency" would have ranked above quite a few real countries in terms of forex trading. If I remember correctly, it was bigger than 70 real nations.
Crypto is the same, except times a thousand.