For what it's worth, Charity Navigator gives them 4 out of 4 stars with a 98.33/100 rating: https://www.charitynavigator.org/ein/200049703
Meanwhile eg the American Cancer Society gets 73/100 and spends more on fundraising than WMF's entire budget, so oncologists can snort blow off hookers in Vegas, but nobody cares.
Not having a ton of extra money is a good way to prevent that kind of bloat.
These campaigns are great to diversify and prevent Wikipedia from being beholden to them.