I used to play WoW back in the days and am mildly interested in the game development afterwards, but somewhere I read that currently some players are able to buy in game time with their game money, so I presume not everyone is actually paying this price. And their most dedicated hard-core players are probably not paying it either.
In reality I don’t know how easy it is and probably casual players are mostly paying subscribers but even back then the game was plagued by a lot of micro transactions.
Additionally we don’t know how much it costs Blizzard to support the servers and run them, as they run a lot of them for sure.