Development on this game has always been relatively slow. Also, they were mostly creating additional content for their other game Overgrown Genesis for most of the time you're referring to. They have started trying out a second artist recently, in order to speed up art production, but if you're looking for a game with quick updates, this isn't it. Who knows, it might speed up with more people doing the art, but somehow I doubt it.
They make 10K on Patreon (and that's before Patreon take their cut and taxes). They are a team of 8 people. That sure sounds like they're getting billionaires by "milking the shite out of their patrons". What do you mean by "the Devs pockets"? and "earn bank off a game this size"? Of course it goes into their pockets. It's called making a living. Should they work on it for free, just because it's a small game?
And did you seriously just compare a mini team of Indies working on porn games with a studio working on a "first person shooter"? Some of you people really need to grow up.