I'm still wondering whether the dev's original motives were altruistic, and he turned greedy, or he planned the entire thing as a get-rich-quick con from the very start.

I'm leaning more towards the latter because, apart from the more recent tantrums, he seems to be quite good at fantastic promises, stalling with vague "everything is under control" replies, and deliberately ignoring questions where a halfway honest reply would incriminate him.