It used to be there was no such thing as prebuying, and yet some of the most beloved games of all time come from that era.
Eh, how many equally good or even better games never got made because they couldn't get the funding?
That being said, it sadly swings both ways. There are a
ton of games that frankly don't deserve the money they rake on Patreon / SubscribeStar / whatever and plenty of projects get to the point where, depending on how charitable you wants to be, one (or more) of few things happen:
a) The developers realize the project is a cash cow and that there is no guarantee (or interest) to accomplish this feat again with a new project. An adult game likely also isn't the best thing to put on your CV when you inevitably need to find a "real" job if one does not already have one. Thus finishing the project would be detrimental to their lifestyle.
b) The spark of creative work extinguishes and dies, turning a passion project into a chore that is ever harder to get back into.
c) The long term issue of being an amateur game developer culminate into a codebase that is utter spaghetti mess that is a massive, time-consuming chore to wade through, grinding any real progress to halt.
d) Constant pandering to fickle audience siderails the original vision to the point that actually progressing any semblance of story becomes nigh-impossible. Perhaps characters you planned to be central to the story are so disliked you need to sideline them and their story, perhaps you caved in to pressure and made side-character(s) more and more central to the story and now need to figure out how to incorporate them into it, only to face audience backlash from said changes.