So, let me weigh in on this. I work in game development myself. Specifically 3D art. It's actually a common practice in the field, for people to take over the development of a project that was abandoned, or stagnated. It even happens in the work I do (I work using 3ds max 2023). The most common reason developers do this, isn't a 'money' thing. Sure, that sometimes happens with AAA companies, but for indie developers, that's rarely if ever the case.
Typically, when someone looks to pick up an abandoned title, it's because that developer is a fan of the title, or the idea presented in it, and want to see it completed. Taking the previous developer's work allows them to expand on the story, perhaps introduce new ideas or concepts, and in essence, collaborate with the previous developer. They pour more time, sometimes even money, into the project and take it further than what the previous developer had. In many cases, the whole reason a game gets abandoned, comes down to time. Specifically, game development takes quite a bit of time. That is time that many people simply don't have, due to other obligations. There are very few "indie" developers who do development full time. They squeeze work in where they can, while also dealing with their other obligations like work, and family, and such. The free time a developer has to work on a project can fluctuate greatly, meaning that while they may have had time to start a project; by the time they come to the decision for abandoning it, they don't have time to continue it.
That's where a secondary developer, or curator as they're often called in the industry, steps in. The new developer offers more time for development of the project, and keeps it alive. It may not be what the original creator expected for the title, as in many cases the new developer will change aspects of it; but that's not always the case. Very often the original developer will be contacted and future changes discussed with them. The new developer will ask what the story was, what the first developer intended, and then work from there.
Developers don't see this as someone 'piggy backing' or benefiting from their work by another person. Honestly, the majority of developers could care less, but it'd take effort to do so. They want to see their project completed, and if it means someone else steps in and takes over the project? So be it, at least the story gets finished. It may not be in the exact way they pictured it, or the story they had planned out, but it's done, and they have learned a great deal from the process. Information that can be used in later titles.