LOL, everyone here posting they flake over money.

Building rep as a dev takes a long time, and you lose it in a heartbeat, and once it's gone, it's not likely fans will trust you again with their hard earned support. Abandoning games isn't a sustainable business model.
The real reason many projects stop, IMHO:
1. No one realizes just how much of an effort it is to make one of these things. They'll eat up every free minute of your and demand more. I became a dev because I loved VN and I wanted to contribute, but truth of the matter is, I hardly have any time to play anything anymore.
2. The hate is something else. You can't imagine how many people will go out of their way to find you and tell you just how absolutely horrible you are and everything you do is, and how much better the world would be without you in it. That can wear a person down until they hate opening up their socials and just want to walk away.
3. Biting off more than you can chew really is a thing. You wanna do everything, put every good idea you have in, but realistically, you can't, and if you're not careful, you can find yourself at at a point where it starts to look like you will never finish this project in your lifetime, and that can be an overwhelming sensation.
Now, I'm sure there's some that are just in it for the money, but those rarely make it past one or two releases, and you can usually tell it's going nowhere from the low effort, cookie cutter quality. Honestly, it's impossible to put the effort in to make one of these things for an extended time if you don't love doing it first. It's just, it doesn't always love you back.