I had one client at the consulting firm I used to work at ask us to basically create a spec (they didn't want anything built until they "were sure we knew everything") for essentially Microsoft Excel for the oil and gas industry.
We asked them to just export the data as an XLSX to let customers use Excel itself and told them they didn't have the budget to recreate a 2 billion dollar R&D product from Microsoft.
Long story short, they paid over 400k for a 800 page spec, and never built it. The consultants involved (myself and others) tried to get our agency to walk, but the money was just too appetizing for the higher ups. It was sad.