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.
It is possible and true, but not a fact, because now even if the project is real, it cannot always come out the way you want, an elementary lack of investment