This guy is inexperienced with making games, pretty sure it's their first game, and for a first game it is extremely ambitious.
The whole quitting deal I imagine is more like a "between my health issues and game complexity, this is hell" but considering they aren't making any/much money from crowdfunding, this would be the most impressive breakaway from a sunk cost fallacy ever recorded if they throw in the towel now.
I'm just waiting, memes always go "2050 release" but at this stage, the meme is true until a new demo is released. As for the old demo being buggy, I have it and I never encountered any major bugs. HOWEVER the dev did share a bug that they had, right before the original March 2020 demo release date, and expressed that they had no idea how to fix it I believe.