The "essay" (for me) read more like a rant about the author's opinions regarding hypothetical situations and how, in many people's views, a successful non-profit spends money. Sure, maybe WMF could spend less but the table looked reasonable. I've donated before and I'm sure I will again because I use Wikipedia all the time. I am going to spend more time learning about the organization and its spending, but as of reading the linked material, I'm unmoved.
Also, I get that 789k is a lot of money. Really more than anyone needs but it's hardly an absurd amount given the norms for CEO pay. Yes, CEO pay is ridiculous but so is the entire economy, speaking as a US citizen. I would have guessed higher and many non-profit CEOs make much more than 789k. Plenty of people, with less responsibility and impact, make more than that so that pay is not really a WMF specific point.
Why should non-profits not want to "rake in tons of cash" if it helps advance the mission of the non-profit?