I reckon the number of sales of the game was pretty irrelevant to them. They lived off investor money for years, and the fact that they released something makes it rather difficult for them to be sued for fraud. I suspect that's why they never took pre-orders, too - it makes it more difficult for any "false advertisement" class action suits to get any traction if they weren't accepting any money.

Here's something that isn't that widely known outside of developers/publishers: Steam holds any money from the sales of a game until the end of the following month - it makes refunds easier, it gives them time to deal with processing fees, etc. So The Day Before's devs, who said they had to shut the studio because they'd run out of money and couldn't afford to stay open because the game hadn't sold well enough, wouldn't have seen any money from the game until next week anyway. And they'd have known this - this wasn't their first game.