But the team then needs to show a completely finished product to its customers in order to continue its development, but most of the projects do not live to the end
I think that most of the projects that, as you say, do not reach the end - these are projects that were initially set up to deceive users and under this guise they hide their fraudulent schemes. If people have a large part of the finished product, they will never give up their years of work.
Now in the modern world it is very difficult to understand where the project is scam, and where it is real, because they are very good at describing and providing everything