They are "Patreon-ware" games. The longer the dev takes to make the game, the more money they make, because it's all crowd funded.

Dr Pinkcake, for example, has 12k members. Patreon has an option to show the actual income but he smartly hides it because I would conservatively estimate that he's pulling in $100k per month.

Still, less of a scam than Star Citizen...