$7b seems wrong. That would require about 40 million subscribers each paying $15 a month. Peak subscribers was 12 million and many would be paying for slightly cheaper long term subs.
They didn't do that much much at the peak of WoW. There were some pets you got by buying the collector's edition of the game but that was it. No paid mounts, no server transfers, no level boosts.
The paid stuff was a monetization tactic after the decline.