I see what you’re saying, it is a lot of memberships taken out of the game, but I would argue no one running a bot farm is paying for membership with Earthly currency. They wouldn’t want to tie legitimate credit information to any of those accounts, and so they obtain membership through bonds purchased with in game gold.
It’s in part what has driven the cost of bonds from 5 million gold to 15 million. As a result, I’m of the opinion that bots aren’t a revenue source for Jagex.
Gone in less than a month, yet not discounted to 1¢. They could do it, just don’t care.