Dis/enchanting is still a big gold source at high levels, so once you reach max level and especially if you're in a guild, you have access to lots more ways to

Dis/enchanting is still a big gold source at high levels, so once you reach max level and especially if you're in a guild, you have access to lots more ways to make money. Which you either spend on raid supplies or to kit out lower-level toons. And there are always the whales who just buy a shit ton of gold and put it in a guild bank.