The need of patent licensing
On one hand, your invention would be a product in the future. By the time your patent application is disclosed and under examination, your competitors will decide around your invention and come up with similar but not identical invention. Therefore, waiting for your invention to be developed into a future product may lose its novelty and value.
Also, inventions may have short-lived usefulness. By the time a patent application is issued, the technology may have taken a different direction, making the invention obsolete.
One the other hand, if implementation of your invention infringes another patent, you are facing a possible expensive litigation process.
In many cases, patent licensing would be a low-cost option, even though the amount of royalty for the license might be significant.

