In 2023, Mozilla spend $230 million dollars on software development. And then they also $6 million on "Grants and Fellowships" (which supports many "green field" open source software initiatives), $1 million on Events (under which the event you're worried about probably falls), and $7 on travel (which probably also includes lots of travel to things like C++ conferences and browser standards conferences and other things that you probably would agree are very mission related, along with the event in question).

So—just out of this subset of expenses, there's probably some other stuff you could take issue with—Mozilla spent money in a 94% ratio on browser development, and 6% on "other stuff", of which probably .001% was this conference in Africa. And I think it's arguable that a lot of that "other stuff" is related technology! But even ignoring that, talking about how we can use the open web to improve life for people in third world countries is exactly the kind of thing that I, personally, would like Mozilla to be doing. And I'm happy for them to spend <5% of their budget on it.