The more money Wikimedia has, the less likely it gets that they keep recurring expenses in a sustainable range. And you can be corrupt without money, true. But

The more money Wikimedia has, the less likely it gets that they keep recurring expenses in a sustainable range. And you can be corrupt without money, true. But corrupt people tend to avoid organisations that don't have a lot of money, they all try to work where the money is. And the do-gooders that are the other group of people likely to push into an org like Wikimedia tend to be particularly defenseless against the first kind.