Having worked for both a small and a mid-size charity (~50, ~500 employees), and known people at others, in my experience an annual "staff party" or similar is usually fairly low-key. People are very aware that the money comes from donations.

Why have the party at all? Because spending €20 or whatever per employee/volunteer on an annual party has benefits beyond increasing everyone's salary by that amount: job satisfaction, employee/volunteer retention, knowledge sharing etc.

Fundraising events are parties for the guests, but work for the charity staff. (Attend the party, introduce Rich Person X to Foreign Princess Y who promotes our work and went to the same university, mention the proposed project in Country Z if she doesn't, etc.)

None of this is in contrast with what I'm saying, no? I would expect an international organization (like Wikimedia) to throw small "staff" parties all over the world, and maybe the CEO would come to some of those to give members at that location recognition.