There are also time constraints in the patenting process. Timing is a very important aspect of invention development. However, for most inventors, speed is important. So, now I'm saying invention development can be very complicated. The fact is, it can be either or both.
Every situation is unique.
The trick is to use simple, common-sense reasoning to answer the complex questions. These answers get you where you need to go. A willing market. Most inventions have value to at least one person in the world, the inventor. The question isn't whether an invention has value or not, the question is how many people will perceive that value and how many of those will be in a position to pay the cost.