So you are saying that if people thought they were contributing to keep Wikipedia running because that is what the ads claimed, its their fault for not going through the financial reports to see where the money is going.
If you raise money saying it is for wikipedia, it should be spent only on wikipedia or IMO it is misleading.
Even "spent only on wikipedia" is a bit complicated -- bawolff's example was grants to Wikimedia Deutschland for work on wikidata, which sounds like it's some separate project. But really wikidata is used pretty extensively inside wikipedia, particularly for keeping facts synched up between the various project languages. Or money spent on Wikimedia Commons sounds like another random project, but actually it's the infrastructure for all the images you see on wikipedia.
It gets fuzzier as you go out to the promotion-of-free-knowledge stuff, for sure. You can argue its connection to keeping information being contributed to wikipedia, and the long term health of the community, but it's definitely less directly keep-the-lights-on.
If you raise money saying it is for wikipedia, it should be spent only on wikipedia or IMO it is misleading.