Their contribution to Wikimedia sends a positive signal to potential customers that is very possibly less useless than the more typical form of corporate signalling: advertising.
Do you think that advertising is also useless signalling?
[1]https://blog.wikimedia.org/2016/11/02/victoria-coleman-chief...
[2]https://upload.wikimedia.org/wikipedia/foundation/6/67/Form_...
[3]https://www.irs.gov/charities-non-profits/form-990-part-vii-...
Here's the 990 for 2016-2017: https://upload.wikimedia.org/wikipedia/foundation/6/67/Form_...
Wikimedia clearly doesn't need as much money, but since it gets it, it grows to spend as much of it as it can. If they scaled back to their spending in 2012 (when they already were high up in the top 10 most visited websites), and did fundraising for only extra 2 or 3 years, they would have enough endowment to fund their operations in perpetuity, and not need to run sad Jimbo face on Wikipedia ever again. Alas, the foundation will expand to fill the available space, wasting millions in the process.
> We've been selling cocaine for the CIA so they could buy arms from Iran? Did we at least free some hostages?
> No, this was about our annual budget.
> What?
> If we don't spend it this year we can't get an increase next year.