[sbuttgereit]

This. I know of someone that invented what appears to be useful medical technology; certain trusted professionals in the field that reviewed the work agreed.

However, some of the case law around what they'd need to patent the turned unfavorable around the time they were pursuing this and looking to turn it into a business. For your reasons 3) and 5), they've shelved it. This was an individual, not a large company, and without sufficient legal protection to reasonably hold large companies at bay, there simply was not sufficient reason to pursue this effort given how questionable the return would be.