It's more the fact that gamedev pays about ~40% of traditional developer work. Adding some sort of idealism on top of that means you'll probably do better flipping burgers than developing an open source game.
Oh, I didn't know game dev paid much less. Thanks for the info. Anyway, it remains the case that making a living as a game dev is far from the only way to get by, and making proprietary software isn't ideal, so "I need to feed my family" remains a sloppy excuse that doesn't justify ignoring the issue. Not that it's irrelevant, but it's not itself adequate.
Not saying that the item in question is itself comparable to this, just there's lots of different ways to get by in the world…