The business model of most (all?) large scale software developers is to sell the client the moon, at low cost, and then step by step make the client pay more an

The business model of most (all?) large scale software developers is to sell the client the moon, at low cost, and then step by step make the client pay more and more for the system, until the client ends up with a very expensive, very hard to maintain system that kinda work, but requires ongoing and expensive "maintenance" work that only the large scale developer can do. It is a very lucrative business strategy. And they get away with it, because of the client decision makers often not being competent enough to make decisions about software systems development.