I don't donate to the WMF because they don't need my money, but I wish they just kept Wikipedia running and made small incremental changes over time for scaling/keeping up to date/adding helpful features. I would of course donate if Wikipedia were at risk of failing (not that it would be that hard to rehost and rebuild it), and they know that and exploit everyone who doesn't realize how rich they are with the annoying begging.
As they say: "The bureaucracy is expanding to meet the needs of the expanding bureaucracy". If you keep giving a nonprofit money, it will keep growing, even if it has more than enough it needs for its earlier charter.