Wikimedia Foundation is funded primarily by small donations (<$100), during its fundraising campaign once a year. You're linking to a page that names donors who contributed $1000+.

Notice that Wikimedia Foundation has little to no influence over the content or community that runs Wikimedia sites. The money is primarily used for running the infrastructure, developing the software, paying the staff (a large percentage of which is spent on tech and legal), and organizing community events.

disclosure: I worked for Wikimedia during the earlier years.