Here is another. I invented and paid for a patent on a device that could save the server industry $6 billion a year. Had it prototyped at a university with grad students over 3 years, prototyped proved key features. It was a pump of small size, needed to cost $5.00 and most important the failure rate needed to be near zero. The nearest competitor $80.00 and offered MTBF of 100,000 hours, needed 1000 years, same as semiconductors. The prototype used plastic and fluid bearings and would exceed failure rate requirements. Did not pursue fund raising. Why? One invester pointed out China could could get around the patent or just ignore them and two the $trillion server industry did not really care about saving $6 billion a year.
Sometimes you discover the business case is dead if you prove the market value but won’t be strong enough to protect it or the industry is just too big too fast moving to care.
But it was a fun project.