You should read this well-reasoned comment from the developers of That Dragon, Cancer about the fact that they’ve not earned any money for their title yet. (They’ve paid off debt, so they have made sales–we’re talking net income.)
The defense I see people throwing around for the Let’s Play videos that have most certainly damaged (not in whole, but in part) the sales for That Dragon, Cancer is that the reason the game has not done well is because it’s the opposite of escapism–“it’s woefully depressing,” writes one commenter on Polygon. “Only a very small percentage of people want to be enveloped in the very real emotional agony and despair associated with what cancer does to somebody’s life.”
But if that’s true, then why would anybody want to watch a Let’s Play of the same thing? Why would someone involved in so-called “mixed media” want to show this game (in full) to other people? Wouldn’t that make them sadomasochists, to subject others to something they suffered through?