Page 21 of their 2024 annual report[1] has expenses listed. About $3,000,000 for web hosting, about $100,000,000 for salaries and benefits out of $178,000,000 total.
[1]: https://wikimediafoundation.org/wp-content/uploads/2025/04/W...
[1]: https://wikimediafoundation.org/wp-content/uploads/2025/04/W...
There is probably a lot to criticize, but you need to go deeper than "salaries" are bad. You need some of those to actually run the website.
There's also the need to support the staff and volunteer developers, which includes wikimedia cloud services, git hosting, config management and orchestration, CI, community hosted tool/bot services, etc.
WMF has ~600 employees, and that's quite lean, for a service of their complexity.