When someone goes to Wikipedia and feels "this was awesome; I want to support this... and OMG, they say they might fail if they don't get money from people like me!" it is absolutely unethical to take their money and spend it on Wikidata, a product this user might have no clue exists and may or may not care at all about. Maybe Wikidata is a great thing, but then the pitch should be "we are glad you enjoyed Wikipedia! don't worry: Wikipedia is safe, as we have more than enough money to fund it! however, we have other projects we think might make a similarly positive impact on the world... maybe you would want to donate to one of them?".